The broad, bipartisan Senate coalition opposed to President Bush’s plan to boost troop levels in Iraq by 21,500 soldiers could come unraveled later this year when Democrats take up the plan’s $1 billion economic reconstruction and stimulus package, with many Republicans and several Democrats already pledging support for Bush’s non-military proposals.

Details of the economic plan, which Bush mentioned briefly in his address to the nation earlier this month outlining his “surge” proposal, are not expected for several weeks or months, but Democratic leadership aides indicated Monday it will not receive a warm welcome from them.

“Democrats are going to carefully scrutinize the proposal. No more blank checks,” said Jim Manley, spokesman for Senate Majority Leader Harry Reid (D-Nev.).

A second Democratic leadership aide said Reid, Minority Whip Dick Durbin (D-Ill.) and other leaders are planning an aggressive oversight process for the plan that will turn a skeptical eye towards the stimulus package’s massive price tag.

“It’s safe to say that the Republican era of see no evil or speak no evil of Halliburton has come to an end,” the aide said.

Reid and Durbin are expected to instruct Appropriations subcommittees with jurisdiction over the various aspects of the Bush proposal to hold exhaustive oversight hearings.

But key Republicans who have backed the bipartisan resolution criticizing the surge — and at least two Democratic Senators — appear much more supportive of the economic aspects of the plan.

Those divisions could be a rare bright spot for an administration that has seen its clout in the Senate significantly eroded over the last several weeks as a result of the Iraq War — including the high-profile defection Monday of former Senate Armed Services Chairman John Warner (R-Va.).

Warner, along with Governmental Affairs and Homeland Security ranking member Susan Collins (R-Maine), Sen. Norm Coleman (R-Minn.) and Sen. Ben Nelson (D-Neb.) unveiled a compromise resolution opposing the troop increase but avoiding some of the stronger language included in a version to be taken up by the Senate Foreign Relations Committee this week.

While the original resolution, written by Armed Services Chairman Carl Levin (D-Mich.), Foreign Relations Chairman Joseph Biden (D-Del.) and Sen. Chuck Hagel (R-Neb.), chaffed some Republican opponents of the Bush proposal because of language they see as too political, the new resolution uses softer language but still includes an explicit repudiation of the proposal.

Democratic and Republican aides said they expected a strong bipartisan coalition to form around the compromise, and Democratic leadership aides said Reid has no plans to oppose the new version. “It’s still a repudiation of the president’s plan,” a Democratic leadership aide said, adding that “we’re not going to get hung up over a word.”

It is far less clear how sizable the opposition will be to the Bush plan’s economic proposals. Despite initial skepticism from Democratic leaders and many rank-and-file Democrats over the plan’s spending provisions, Republicans appear to be much more unified in support of those aspects and have at least two Democratic backers.

At a press conference Monday announcing the compromise surge resolution, Warner pledged his support for the economic package and said his GOP colleagues will also back Bush’s plan to pump dollars into the Iraqi economy.

A GOP leadership aide said that at this point the Republican Conference is largely united in support of that proposal.

Sen. Joe Lieberman (ID-Conn.) — who as chairman of the Homeland Security and Governmental Affairs Committee would have oversight jurisdiction over the stimulus package — was an early supporter of Bush’s entire surge package.

In fact, while Lieberman has found himself as the sole Democrat supporting the troop increase, he may be joined by other Democratic moderates when the debate turns to the proposal’s economic provisions.

An aide to Nelson said Monday that the Nebraska Democrat also would back Bush’s economic package.

However, with at least several weeks to whip their Caucus and woo potential Republican defectors, Senate Democrats could cobble together enough support to either significantly curtail or block the proposal.

One Democratic leadership aide last week pointed to polling data presented by Durbin at the Democrats’ weekly luncheon indicating higher public opposition to the spending package than to the troop surge itself.

And with the annual budget and appropriations fights looming, Democrats could use the increasingly tight federal funding levels as leverage to bring more Members into the fold.

Conservative House Democrats have already begun a push on greater fiscal oversight and accountability in Iraq, a move that could end up helping efforts to rein in Bush’s plan in the Senate.

On Friday, the conservative Democratic Blue Dog Coalition announced a push to increase fiscal accountability of the war, calling for a number of actions to better scrutinize the Bush administration’s spending and to control the skyrocketing costs of the conflict.

Blue Dog Co-chairman Mike Ross (D-Ark.) announced that the group would introduce a resolution calling for greater fiscal accountability in the war that would include a call for greater spending transparency, creation of a “Truman Commission” to scrutinize contracts, a call for war funding to be done through the normal appropriations process rather than supplemental spending bills, and the use of “American resources” to improve the ability of the Iraqi government to take control of its policing activities.

Meanwhile, House Republican lawmakers on Monday called for the creation of a bipartisan select committee to conduct oversight of the administration’s latest Iraq strategy.

The Republican proposal, which echoes the president’s call for a bipartisan working group on the broader war against terrorism, would establish an evenly split 10-member panel, made up of members of the Armed Services, Appropriations, Foreign Affairs, Homeland Security and Intelligence panels.

In addition, the GOP plan would institute a series of benchmarks to gauge progress made by the U.S. and the Iraqi government under the new strategy and would require those entities to report to Congress every 30 days for review.

“We have to candidly and honestly assess whether the new strategy is successful,” House Minority Leader John Boehner (R-Ohio) said at a press conference announcing the proposal. The measures range from progress made in preventing insurgents and terrorists from using Iraq as a “sanctuary” to providing equal access to resources to all Iraqis.

Exempt from the new benchmarks, however, would be definitive deadlines for any portion of the plan.

“If you try to put hard dates in here, you’re probably asking for a failure,” Boehner said and later added: “By measuring the benchmarks, we’ll have early indications of what we’re doing.”

Boehner asserted the body would be “more efficient” than monitoring the new strategy through the current committee structure.

He later added: “I’ve made it clear to the president that support on the Hill among Republicans remains strong.”

But in a letter to Bush on Friday, Reid and Speaker Nancy Pelosi (D-Calif.) quashed the president’s proposal for a bipartisan working group, asserting that Congress is already prepare to develop policies addressing terrorism.

“We look forward to working with you within these existing structures, in a bipartisan and fully consultative way, to make progress on efforts against terrorism and other important matters,” the letter states.