With the exhausting pace set by the 2008 presidential contest pushing candidates to engage earlier than ever before, it should come as little surprise that some of the ferocity has trickled down to the class of Senators up for re-election in 2010.

Two lawmakers in the group, GOP Sens. Chuck Grassley (Iowa) and Arlen Specter (Pa.), already have announced plans to run again — some 44 months before voters go to the polls to decide their fate.

Specter, 77, and Grassley, 73, are each seeking a sixth term.

But both Democrats and Republicans alike say the Senate duo won’t be lonely for long in an evolving political landscape that, these days, requires millions of dollars and countless campaign hours.

“It’s just getting earlier, and earlier and earlier,” said Sen. John Ensign (Nev.), chairman of the National Republican Senatorial Committee. “And I don’t think it’s going to go in the other direction.”

Ensign is charged with re-electing 20 Republican incumbents this cycle, holding on to one open seat now occupied by retiring GOP Sen. Wayne Allard (Colo.) and trying to pick off a few Democratic-held seats. Given the hurdles faced by incumbents in 2008, it’s no surprise that Senators already are gearing up for 2010, he said.

“It wasn’t that way that long ago,” Ensign said. “Now you need one and a half to two years minimum. At this point, you have to raise so much money. The challenge is so huge.”

Campaign fundraising reports covering the first three months of the year and filed earlier this week offered an early glimpse of the round-the-clock campaigning that has become commonplace in the modern political world — especially for those Senators who are considered potentially vulnerable.

Specter, for instance, posted one of the largest first-quarter hauls of all 34 Senators whose terms will expire at the end of 2010.

He raised $587,000 from Jan. 1 to March 31 and ended last month with almost $1.1 million in the bank.

One of the few Senators up in 2010 to raise more than Specter was Majority Leader Harry Reid (D-Nev.), who raised $851,000 in the first quarter and had $935,000 in the bank at the end of the period.

Specter, a moderate who faced a tough primary challenge from conservative then-Rep. Pat Toomey (R-Pa.) in 2004, recently told The (Harrisburg) Patriot-News that he would “be foolish” if he weren’t preparing for a similar battle in 2010.

Asked whether he believed it was premature, Specter told the Pennsylvania newspaper: “Well, it isn’t for fundraising. Listen, last Senate race in Pennsylvania cost $31 million. You know what that is on an hourly basis?”

Specter’s campaign spent $20.3 million in his 2004 campaign, more than half of that in the primary.

The Wall Street Journal reported last month that Specter, the ranking member of the Judiciary Committee, recently met with wealthy donors at Donald Trump’s 18-acre Mar-A-Lago golf resort in Palm Beach. The event was organized by GOP media consultant Roger Stone, a longtime Specter political adviser.

Sen. Mel Martinez (R-Fla.), who also could face a difficult re-election in 2010, is gearing up for his own race even as he’s taken on new duties this cycle as general chairman of the Republican National Committee.

Martinez raised $243,000 in the first quarter of 2007 and had $458,000 in the bank on March 31.

The Wall Street Journal also reported that Sen. Orrin Hatch (R-Utah), who was just re-elected in November and isn’t up again until 2012, attended a fundraiser for his benefit last month in Palm Beach.

There is no doubt that with next year’s White House contest already being billed as the first-ever billion-dollar political race, Senate campaign costs are hitting new highs as well. In 2006, the average amount spent by both sides in the 10 costliest Senate contests was $34 million, about twice as much as the $17 million spent in 2002 to win a Senate seat, according to the Center for Responsive Politics.

Four of the 34 lawmakers up for re-election in 2010 currently are running 2008 presidential campaigns and therefore putting little effort into raising money for their Senate campaigns. Still, most of the money they amass for their national campaigns can — and no doubt will — be transferred back to their Senate accounts if their White House bids prove unsuccessful.

Those in the group include Sens. Barack Obama (D-Ill.) and John McCain (R-Ariz.) — who are vying in the first tier of contenders for their respective parties’ nomination. Sens. Sam Brownback (R-Kan.) and Chris Dodd (D-Conn.) also are running for president but face longer odds.

McCain, whose lagging presidential fundraising was one of the biggest storylines to come out of the first-quarter reports, had just $26,000 in his Senate account at the end of March. Dodd had just $15,000 in his Senate coffers, after transferring $4.7 million into his White House account.

The opposite is true, however, for Sen. Evan Bayh (D-Ind.), who is up in 2010 and decided against a 2008 bid for the White House after laying the groundwork to run.

Bayh raised just $140,000 in the first quarter of the year but showed $10.4 million in the bank — a cash-on-hand figure rivaled perhaps only by Sen. Richard Shelby (R-Ala.) in the 2010 class. Shelby showed $11.8 million in reserve at the close of last month.

Like his colleagues, Bayh said the “exploding costs of campaigns” is a new reality of national politics. The Senator said that when his father, former Sen. Birch Bayh (D-Ind.), served in the chamber, Members “didn’t even think about their elections in the first four years of their terms.”

“Unless something happens to reduce the cost or the length of the campaign, the trend will continue,” Bayh said. “The reality is a system that’s different. Senators are no different than they used to be. It’s just they are reacting to a system that’s different than it used to be.”

Bayh is one of 15 Democratic Senators in cycle in 2010, compared to 19 Republicans. Many of those incumbents undoubtedly will face comfortable roads to re-election, but as recent cycles have shown, even some of the “safe” Senators can encounter surprisingly difficult races.

Sen. John Thune (R-S.D.), who faces reelection in 2010 and already is starting to raise money, said Senators can’t afford to take their re-elections for granted and have to start laying the groundwork sooner than ever.

Thune narrowly knocked off then-Minority Leader Tom Daschle (D-S.D.) in 2004, and the first-term Senator could be targeted by Democrats eager to extract revenge.

“We’re in the world of 24/7, virtual politics,” Thune said. “In my case, it’s almost like a permanent campaign.”

Thune raised $150,000 in the first quarter but showed a war chest of $2.1 million.

“Everyone realizes you don’t want to get flat-footed,” Thune added. “The best way to arm yourself is to raise money and let everyone know what your intentions are. You don’t want to leave any doubt. You don’t want to give any hope to a prospective opponent.”

Andrea Kemp contributed to this report.