Updated

Democratic and Republican House leaders have been whipping back and forth across the country on a whirlwind tour in support of their party colleagues seeking to hang on to or win congressional seats.

With a GOP majority as slim as it is, their vigor, gravitas and fund-raising prowess is considered a big favor in many tight district races.

"It certainly reflects the closeness of the margin in the House," John McGovern, who works with House Speaker Dennis Hastert (search) on behalf of Keep Our Majority Political Action Committee (search), said of the willingness of leaders to travel. Hastert, by McGovern's estimation, has participated in 495 events for congressional candidates in the last two years.

"[We're] certainly taking advantage of every opportunity to pick up new seats," McGovern added.

On the Democratic side, the schedule is no less grueling. According to Stacy Kerr, spokeswoman for the Democratic Congressional Campaign Committee, House Minority Leader Nancy Pelosi (search) of California has traveled to about a dozen states since late August, and planned a sweep of another 10 states between mid-October and Election Day, Nov. 2.

House Majority Whip Roy Blunt (search) has been attending events for an average of three candidates a day, sandwiching the visits between his congressional duties in Washington and district events at home in Missouri.

On Columbus Day, spokeswoman Jessica Boulanger said Blunt campaigned for Melissa Brown and Mike Kirkpatrick, two Republicans competing for open seats in Pennsylvania. He then flew over to Indiana to show his support for Rep. Jerry Weller in Illinois.

"Typically, it's what his day looks like when he's out in the field for candidates," said Boulanger.

"It impacts our majority and Congressman Blunt as the whip of the House understands very well the importance of having a comfortable majority and bringing as many of these Republican candidates back to D.C. as possible," she added.

The House is now made up of 229 Republicans, 205 Democrats and one independent who votes with the Democrats. Democrats would have to gain 13 seats to take over the majority, but political analysts say it's not likely, though they stand to gain some ground.

In all, about a dozen "toss up" races throughout the country and a few other district stopovers for good measure are keeping these party surrogates hopping.

Political science professor Larry Sabato, director of the University of Virginia Center for Politics, said that the level of campaigning on behalf of leadership surrogates is unprecedented. He blames "intensification" of politics, fund-raising and the polarization of the country.

"Twenty years ago," he said, "you almost always saw the speaker of the House in Washington, at least while Congress was in session. [Leaders] were at their desks in Washington, and they went back to their home districts when appropriate," Sabato said.

He said the pace these members are going is causing them "to look tired and burned out. That's not a good thing."

But the candidates and state parties couldn't be happier for the visits -- whether it be a rally in the candidates' district or a private fund-raiser -- and the visits are often highlighted in campaign literature, on candidates' Web sites and to reporters.

After a June visit from Blunt, Brown, who is running a tight race against Allyson Schwartz for the open seat in the 13th District, suggested he helped raise her credibility in Washington.

"The visit is increasing evidence that the eyes of Washington, D.C., are focused squarely on the 13th district and the strong candidacy of Dr. Brown," said a June 21 press release.

Democratic Minority Whip Steny Hoyer of Maryland has campaigned in more than 35 districts in 22 states so far this year.

"I hope to bring attention to the Republican Congress' failures," on health care, national security, jobs and help for the middle class, he said.

But in some districts, the leadership is sure not to tread. Those typically are districts where an incumbent or challenger is campaigning among constituencies that trend toward the opposite party, or in fairly split districts where moderates rule and party fist-wavers are asked to stay away.

For instance, Nick Clooney, Democrat in Kentucky, is running for an open seat in the conservative 4th District and has made it clear his campaign needs no help from Democratic leadership.

"We've asked them not to campaign for us. We can stand on our own two feet," said Clooney campaign spokesman Bob Doyle, in an interview with FOXNews.com.

And while Hastert might not raise too many hackles among moderates, one is sure not to see Majority Leader Tom DeLay in tight open seat races in New York, Georgia or Pennsylvania, where the socially conservative firebrand would likely not play well.

Some have suggested that recent admonishments of DeLay by the House ethics panel for alleged fund-raising irregularities have reduced the leader's energetic campaign schedule. But aides say privately he hasn't slowed down at all.

A Louisiana-based Times-Picayune article published Sept. 28 suggested that DeLay scaled back campaigning for Republican Billy Tauzin III, who is running to replace his father in Louisiana's 3rd District, because of the ongoing controversy, which extends to DeLay's PAC and associates. DeLay's people have denied any connection between the investigations and his schedule changes.

"Clearly, DeLay was one of the most active leaders in building the majority and setting up STOMP and ROMP" (leadership PACs), and he continues to raise money and campaign actively, said one Republican on Capitol Hill who did not want to be named. "Even his critics are concerned that he gets Republicans elected."

Asked what effect all the hectic campaigning has on the legislative process, especially since election cycles seem to get longer every two years, Sabato said, "it can't help."

"But they do what they got to do, they always have and they always will," he said.