Campaign promises are a tricky thing for candidates to any office, but none more so than the Senate, where short of a filibuster-proof 60 votes, majorities have long found their agendas stymied by even a lone Senator.

Like their House counterparts, then- Senate Minority Leader Harry Reid (D-Nev.) and Democratic Senatorial Campaign Committee Chairman Charles Schumer (N.Y.) spent much of 2005 and 2006 castigating the GOP majority as a “do-nothing Congress” and vowing to bring “a new direction” to the chamber.

At the top of their to-do list: an end to the Iraq War, which the public had lost its patience for by the middle of 2006. Virtually every Democratic incumbent and challenger in the ’06 cycle wove promises to bring the unpopular war to a close alongside other popular campaign pledges, such as a permanent fix to the alternative minimum tax, ethics reforms, immigration overhaul and increased spending on veterans’ issues.

And, after more than a decade of GOP dominance of Congress — the last several of which were plagued by scandal — the public turned the keys over to Democrats.

While Speaker Nancy Pelosi (D-Calif.) was able to quickly churn through dozens of campaign promises, big and small, thanks to the Speaker’s nearly unlimited power, the Senate ultimately became a campaign pledge burial ground of sorts for much of the Democratic agenda. With a one-vote majority on most issues — and, on the war, operating from a deficit thanks to the defection of Sen. Joe Lieberman (ID-Conn.) — and a Republican minority that despite low spirits remained largely loyal to President Bush, Reid found himself repeatedly stymied.

“You can look at the voting record and the ample time Democrats spent on the floor debating these issues and trying to move them towards completion while Republicans stood in our way happy to endorse the status quo,” a senior Democratic leadership aide said.

Indeed, the list of so-far unfulfilled campaign pledges is significant — immigration overhaul collapsed, the AMT has yet to be fixed, Democrats have been unable to move a package of spending offsets and, most significantly, Reid and Pelosi have been unable to even come close to forcing an end to the Iraq War.

In the sort of “turnabout is fair play” maneuver, Senate Minority Leader Mitch McConnell (Ky.) and other Republican leaders quickly picked up the “do-nothing Congress” drumbeat.

That is not to say Democrats have not made significant gains legislatively over the last two years. Reid successfully pushed through a GI bill, expansion of veterans’ health care, a farm bill, legislation requiring the implementation the 9/11 commission’s recommendations, ethics reform and consumer safety rules.

Additionally, an alliance that included Democrats, Bush and current GOP presidential nominee Sen. John McCain (Ariz.) was on the verge of agreeing to a sweeping immigration bill in 2007, only to see the carpet pulled out from under them at the last minute when conservatives rebelled against the deal.

Democrats concede that some of their failures are a result of internal disputes within their own party — most notably tax issues — and, in the case of Iraq, the fact that they underestimated the GOP loyalty to Bush.

But they contend that most of the blame rests with Republicans who have used the Senate’s filibuster rules to frustrate Democrats at every turn. “On the most pressing issues of our time, every time Democrats tried to advance those issues … Republicans stood in the way,” the Democratic leadership aide said.

Although Republicans have vigorously denied charges of obstructionism, privately they acknowledge that stalling techniques are one of the minority’s few effective tools.

Mindful of the way Democratic and Republican Minority Leaders before him had used the rules to their advantage, McConnell spent much of the past two years in procedural duel with Reid, repeatedly forcing the Democratic leader into filing cloture motions, often in cases where both sides knew the bill would pass unanimously.

In the House

House Democrats came to town with their newly minted majority in 2007 with a massive agenda and a boatload of promises — they wanted to end the war, bolster health care programs, increase college affordability, pass ethics reforms, re-enact pay-as-you-go rules and increase the minimum wage. House Democratic leaders were able to muscle their agenda, including their “Six for ‘06” package, through their chamber but ultimately were defeated on many of their top priorities by presidential vetoes and concerted Republican opposition in both chambers.

By far the party’s top priority, and a key reason for their majority status, was a desire to end the war, and leadership trotted out vote after vote, calling for timelines to end the war and opposing President Bush’s troop surge. But the bravado of leadership ran into the president’s veto pen and a stiffened Republican Party spine, led by Minority Leader John Boehner (Ohio), who lost only two GOP votes.

Pelosi was forced to back down because many Democrats, led by Majority Leader Steny Hoyer (D-Md.), did not want to take the huge political gamble of voting to cut off funds for troops in the field. Ultimately, Pelosi voted against the war funding bill and Hoyer for it.

It was far from the only defeat Democrats would face. In addition to Iraq timelines for withdrawal, embryonic stem-cell research, a major expansion of children’s health insurance and increases in domestic spending all fell to vetoes in 2007. And PAYGO principles — while applied to most bills — were sometimes shredded in the face of GOP opposition to tax increases. Although the House repeatedly passed an AMT relief with offsetting revenue increases, Democrats ultimately waived PAYGO after Senate Republicans blocked any offsets. Democrats could point to several major victories — an increase in the minimum wage, passage of the bulk of the 9/11 commission’s recommendations, a new ethics law, a cut in student loan rates and a big energy conservation bill with a 40 percent increase in vehicle mileage standards over the next decade as its centerpiece. And they successfully overrode Bush’s veto of a water projects bill filled with earmarks.

But 2008 has been even less kind, as the year has been nearly swallowed by soaring gas prices, the housing crisis and election-year politics.

After quick bipartisan agreement on a massive stimulus package, which cut taxes for individuals and businesses, and a bipartisan vote to override Bush’s veto of the farm bill, partisan warfare ruled the day, with Republicans seizing on the issue of expanding oil drilling and Pelosi taking extraordinary steps to avoid a vote.

Much of the Democratic agenda stalled.

Pelosi’s hope of passing cap-and-trade legislation to fight greenhouse gas emissions went up in smoke after Bush failed to offer strong support and the Senate failed to act. Bipartisan talks on the festering issue of illegal immigration and temporary work visas collapsed. And prospects for appropriations bills dimmed when Bush issued a pre-emptive veto threat against any bill spending more than he requested.

With polls suggesting Democrats would gain seats and possibly the presidency, Democrats started to run out the clock on the year in hope that a new president would be easier to work with. After repeatedly blasting Republicans for failing to get their budget work done in 2006, Democrats passed a budget resolution but then ditched this year’s appropriations bills almost entirely, both to avoid votes on drilling and Bush’s promised vetoes. They also avoided a messy floor fight over earmark spending.

And Democrats capitulated quickly on the Iraq funding bill — adding even more than Bush initially requested without strings attached — just to get it off the table. Democrats did manage to get some big wins in return for that capitulation by tacking on an extension of unemployment benefits and an expensive GI bill benefit resisted by Bush and many Republicans that ensures full funding for four-year college educations for veterans. But as with the AMT fix and hundreds of billions spent on wars and other “emergency” spending, the new GI bill will add to the deficit because Republicans balked at paying for it with a tax increase on the wealthy.

Republicans also beat Democrats into submission on warrantless wiretapping, albeit with a few tweaks nodding at the concerns of civil libertarians.

Pelosi, in the meantime, took a hostage — bottling up the Colombia free-trade agreement by nuking the fast-track process to gain a precious, and rare, bit of “leverage” that she hoped would lead to GOP support for items such as a second stimulus package and more spending on displaced workers. But that leverage hasn’t yielded much in the way of results, and the agreement remains in limbo.

Democrats also spent much of the year urging Bush to take more aggressive action on the housing crisis, with a major bipartisan housing overhaul quarterbacked in the House by Financial Services Chairman Barney Frank (D-Mass.) ultimately signed into law despite opposition from many House Republicans who derided it as a bailout.

But the steady march of gas prices to new records higher than $4 a gallon came to dominate House politics, and Pelosi’s promises of an open-floor process and rights for the minority that she had fought so bitterly for when she was in the minority went almost completely by the wayside — even more than the year before.

Partisan Sniping

Pelosi and Democrats pointed to numerous initiatives blocked by Republicans — including a sale of oil reserves, clamping down on speculators and forcing oil companies to accelerate drilling on land already under lease — but went home with little to show for months of legislating besides a bill that forced an end to new strategic oil purchases. Pelosi repeatedly brought the bills up under suspension rules to avoid having to vote on any Republican alternatives or amendments.

Pelosi’s muzzling of Republicans — even adjourning for the August recess without giving the GOP the opportunity to offer dozens of speeches they had planned before the television cameras on the House floor — prompted an unprecedented, five-week protest by Republicans in the dimly lit, microphone-free chamber in front of tourists. Republicans repeatedly accused Pelosi of failing to deliver on a 2006 promise for a “common-sense plan” to lower gas prices and a promise for a more open Congress, and beat up Democrats all summer over Pelosi’s refusal to allow votes on opening new areas for oil drilling.

But when Democrats returned in September, the GOP had the upper hand, and Pelosi was forced to retreat on her long-held opposition to drilling in the face of demands from her own Members and the looming Sept. 30 expiration of the offshore drilling moratorium.

Pelosi repeatedly talked of moving a second stimulus package — and still plans to — but has yet to get support from Republicans for another round of unemployment benefits, aid to states, increased food-stamp benefits, energy assistance for the poor or new infrastructure spending.

But like many other proposals from the Democrats this year, the package has yet to materialize.