By Greg Giroux, CQ Staff

Losing an election by just a little can create a lot of temptation for a candidate to try again, figuring that an earlier start, a change in strategy or some other campaign tweak will produce a victory on the second try. That is why there typically are several rematch contests in each congressional election cycle.

But the second time, it turns out, is rarely the charm for challenging candidates, and their track record in this year’s round of rematches was no exception. Eighteen races in which the same major-party candidates faced off for the second consecutive election were rated as at least somewhat competitive by CQ Politics. And in 15 of those 18 contests, the same candidate won both elections.

In fact, the defeated challenger candidates in a dozen of those races actually lost ground, with the incumbents winning more handily in the second round.

Of the three exceptions to the rule, the one with the highest profile came in New Hampshire’s race for the U.S. Senate. In this year’s only Senate rematch, Democrat Jeanne Shaheen, a former governor (1997-2003), defeated one-term Republican Sen. John E. Sununu , reversing the outcome of their first showdown in a 2002 open-seat race. Shaheen, who lost in 2002 by 4 percentage points, this time won by 6 points.

Shaheen benefitted from a political environment that had greatly shifted in the six years since her first Senate try. It was the Republican Party that had national political momentum in 2002, and a tradition of “Yankee Republicanism” still was strong in Shaheen’s home state of New Hampshire. But the national surge favoring the Democrats over the past couple of election cycles took hold in New Hampshire, which has joined in the longer-running Democratic trend throughout the New England region.

In the two House rematches in which the outcomes flipped this year — also both Democratic pickups — the challengers were political newcomers when they first ran in 2006, and both benefitted greatly from the familiarity they had built among voters.

Larry Kissell, a social studies teacher and former factory worker from North Carolina’s 8th District, defeated five-term Republican Rep. Robin Hayes , to whom he had lost by just 329 votes in the nation’s second-closest House race of 2006. Eric Massa, a Navy veteran and former Pentagon aide from New York’s 29th District, defeated two-term Republican Rep. John R. “Randy” Kuhl Jr. by 2 percentage points two years after Kuhl won their first matchup by 3.

But far more often than not, rematch candidates fail. Part of the reason is that the winning candidates, with another term of incumbency providing them with bragging points, often gain political strength between the first and subsequent matchups. And rather than greet second-time candidates as familiar faces, some voters come to view them as perpetual office-seekers who should have stepped aside and allowed new challengers to run.

Rematch candidates also can run aground when their comeback strategies turn out to be predicated on a false hope. That happened to some Republicans, including a handful of past incumbents, who ran again after losing in 2006, which a 30-seat loss made the GOP’s worst election year since 1974.

The political environment in 2008, they thought, could not possibly be as bad for the party as it was in 2006. But they found out, to their chagrin, that it was.

Former three-term Republican Rep. Melissa A. Hart tried to reclaim the seat in western Pennsylvania’s socially conservative 4th District, where she lost the 2006 race to Democrat Jason Altmire by 4 percentage points. But Altmire, a former hospital association executive who worked during his freshman term to build a profile as a centrist Democrat, deflected Hart’s effort to cast him as too liberal — and saw his winning margin balloon to 12 percentage points, even though the district was no stronghold for Democratic presidential winner Barack Obama .

Republican Anne M. Northup lost the House seat she’d held for five terms by just a bit more than 2 percentage points in 2006. But she hadn’t planned for a rematch against Democrat John Yarmuth in Kentucky’s 3rd District, which includes Louisville and its suburbs.

In fact, Northup had turned around quickly after her 2006 loss to run in the 2007 Republican primary for governor, which she lost, and was recruited by GOP officials to run for the House again only after their preferred candidate withdrew to fulfill a military obligation. Yarmuth’s high visibility in Kentucky’s most Democratic-leaning district, combined with the sharp downturn in Northup’s fortunes, enabled the freshman incumbent to win his rematch by nearly 20 percentage points.