From Florida to California, third-party candidates pulling a point or two of the vote on Election Day might make the difference between winning and losing.

‘Forty-seven is the new 50,’ a Democratic official closely watching House races told Roll Call.

There are third-party House candidates in at least a dozen districts who will draw votes from Republicans and Democrats. In a regular election cycle, that might prove irksome, but this year it could be a blessing for embattled incumbents hoping to hold on to their seats during a rough night.

Perhaps most prominent on tomorrow’s map is Nevada, where Senate Majority Leader Harry Reid (D) remains locked in a neck-and-neck battle with tea party favorite Sharron Angle (R). Reid hasn’t been able to crack 50 percent in the Tossup-rated race, but if ‘none of these candidates’ and a Nevada Tea Party candidate attract enough attention today, he won’t need to.

A series of close House contests could fall the same way, with either tea party or libertarian Independent candidates poised to play spoiler and help Democrats. Democrats who might be boosted in such races include Rep. Tom Perriello in Virginia’s 5th district, Rep. Bill Owens in New York’s 23rd district and Rep. Baron Hill in Indiana’s 9th district ‘ all rated as Tossup races.

Operatives for both Republicans and Democrats think that’s the case in Florida’s 12th district. Lori Edwards (D) and Dennis Ross (R) are running for the seat Rep. Adam Putnam is vacating to seek statewide office. But Polk County Commissioner Randy Wilkinson, a former Republican, is running as a third-party candidate under the official Florida Tea Party label.

This race is rated Leans Republican, but election watchers say it will be tight. A GOP source said this is one district the party thinks could be a ‘surprise’ and slip away.

In Virginia’s 5th district, state Sen. Robert Hurt (R) is favored to unseat Perriello. But Democrats still hold out hope thanks in part to the third-party candidacy of Jeffrey Clark.

Hurt frustrated some tea party activists because he backed a $1.4 billion tax increase under then-Gov. Mark Warner (D) in 2004, and he was the Washington establishment’s top choice to win in a competitive primary this summer. Hurt has refused to debate Clark, who has accused Hurt’s operatives of dirty tricks to force him off the ballot. Clark has barely registered in polls, however.

Both Democrats and Republicans think the conservative American Constitution Party could boost Democrats’ chances in Colorado, where the Republican gubernatorial candidate Dan Maes has tanked and former Rep. Tom Tancredo, who is running as the Constitution Party nominee, is in second place. Tancredo’s success could boost turnout and votes for fellow third-party candidate Doug Aden in the 4th district, where Rep. Betsy Markey (D) appears set to lose her seat to Cory Gardner (R).

Hill is in a close race with Todd Young (R), and Indiana Democrats have sent mailers boosting Libertarian candidate Greg Knott in hopes of splitting the Republican vote.

Republicans said they aren’t worried and believe they will net more than enough Democratic seats to win control of the House. And in at least one race, a third-party candidate could work in their favor as they aim to unseat Rep. Loretta Sanchez in California’s 47th district. She faces Van Tran (R) as her main opposition, but a GOP source said liberal third-party candidate Cecilia Iglesias could split the Hispanic vote. Sanchez was snared this fall in a mini-controversy by suggesting that ‘Vietnamese’ are trying to ‘take this seat.’ This race rating is Leans Democratic.

In upstate New York, third-party candidate Doug Hoffman, a conservative who lost a special election earlier in the cycle for the same seat, dropped out of the race to endorse GOP candidate Matt Doheny. But Hoffman’s name remains on the ballot, a glitch that could help Owens keep his seat for a full term.

On the Senate side, a third-party candidate complicates the math for Illinois contenders Alexi Giannoulias (D) and Rep. Mark Kirk (R). Sen. Lisa Murkowski (R) could win re-election with a third of the vote since she is a write-in candidate following a primary loss to Joe Miller (R). The Democratic Senatorial Campaign Committee this weekend did a late ad buy for nominee Scott McAdams in hopes of the intraparty war boosting its candidate.

But Reid is the most likely to be betting on third-party contenders. Nevada state legislators in 1976 put the none-of-the-above line on their ballots as a response to Watergate, opting to allow residents a protest vote. It’s the only state in the union with such an option, and this year is all the more relevant since Nevada voters have repeatedly told pollsters they don’t like either main-party candidate.

Reid is no stranger to close elections ‘ the lone exception being 2004 when he won 61 percent of the vote. That year, ‘none’ pulled in 1.6 percent.

In 1998, Reid barely won re-election, earning just a few hundred more votes than now-Sen. John Ensign (R) and 47.9 percent of the total vote. That year, ‘none of these candidates’ garnered 1.9 percent, the same percentage as a Libertarian on the ballot.

David Damore, a University of Nevada at Las Vegas political science professor, said this year’s results will closely resemble 1998. ‘None of the above’s total is probably going to be bigger than the difference between them,’ he said. ‘Neither of them are likeable.’

There is also a conservative Independent American Party candidate on the ballot.

State elections spokeswoman Pam DuPre said that although ‘none’ once won a primary in the 1970s, it is a nonbinding choice. The office would go to whichever candidate earns the second-highest number of votes.

Longtime Silver State journalist Jon Ralston predicted over the weekend that ‘none’ would get 4 percent.