Tuesday's U.S. election will end up making history, regardless of the outcome. If the Democrats win, Barack Obama will be the first African-American president in U.S. history. If the Republicans take the White House, Sarah Palin will become the country's first female vice-president.

But while the exciting presidential race has been the focus of much media and voter attention, Tuesday night may also end up being a watershed occasion for the Senate and House of Representatives. If the polls are correct, the Democrats may be tantalizingly close to reaching the "magic 60," the coveted-60-seat senate majority they would need to override opposition filibusters.

What some are calling a "damaged Republican brand" also bodes well for Democrats running for the House, where analysts say they could gain anywhere from about 15 to 30 seats. If they win congressional majorities and the White House, the Democrats will have control of all three levers of political power in Washington for the first time since President Bill Clinton's first term.

The Democratic onslaught has the GOP putting their limited resources into some close races in an effort to prevent a repeat of 2006, when they lost majorities in both the House and Senate. Here are some bellwether Senate and House races to watch on Tuesday night that could dramatically shift the makeup of Congress.

Minnesota, senate seat

The race for a senate seat in Minnesota has been one of the nastier fights of this election cycle. In a state that has elected a wrestler as governor and a leftist college professor to the senate, it may be no surprise a former comedian is giving the Republican incumbent, a former Democratic mayor, a run for his money.

Republican Sen. Norm Coleman and Democratic rival and former Saturday Night Live actor Al Franken have waged a bitter battle exchanging nasty barbs throughout the campaign. Franken has accused Coleman of being a George Bush sycophant, while the Coleman campaign has said Franken is a sexist, foul-mouthed writer-of-porn.

The campaign fight has become so intense that lawsuits have been flying on both sides. Coleman is suing Franken for slander and, at the same time, a Texas businessman is suing the senator for $75,000 in alleged secret payments he claims he gave Coleman's wife.

However, the insults, lawsuits, and millions of dollars in campaign attack ads haven't given either side much of an advantage. Surveys indicate Franken and Coleman are running neck-and-neck and within the margin of error in most polls.

North Carolina, senate seat

If there's one congressional fight in the country that's telling Republicans just how dire their chances appear to be this year, it's the battle between Elizabeth Dole and Democrat Kay Hagan. Dole, the incumbent senator and wife of former GOP senator and 1996 presidential candidate Bob Dole, was trailing Hagan by 3.4 per cent in Real Clear Politics' average at the end of October.

The possibility of losing has Dole going on the offensive in the days before the election, even suggesting that John McCain may not win come Tuesday. One of the arguments she has been making in a campaign ad suggests that she should be returned to the senate to counterbalance a Democratic White House.

A Dole ad hit her opponent so hard that CNN's Campbell Brown devoted a special comment to it. The ad accused Hagan, a former Sunday school teacher, of accepting money from "godless Americans." Campbell was so outraged about the "ridiculously misleading" ad that she called on Dole and all negative campaigners to "Reclaim your dignity!"

Florida, house of representatives

If there's a silver lining for the Republicans in the House this year, it's in Florida's 16th District. This was Mark Foley's old seat. He's the former Republican who created a scandal after he allegedly sent inappropriate emails of a sexual nature to teenage congressional pages.

Democrat Tim Mahoney swept to victory in 2006 promising to bring family values and integrity back to the elected office. The man dubbed the "accidental Congressman" is now facing an uphill climb after a major news organization reported that the married politician had a mistress.

The report also said he allegedly paid her off after firing her from her job with his campaign. Recently, there have been allegations of another Mahoney affair. Republican businessman Tom Rooney, who was down by about 7 points in a poll conducted for his own campaign in September, now reports he's ahead of Mahoney by 26 points.

Alaska, senate seat

The last time a convicted felon ran for office, shamed Democrat James Traficant tried to retain his congress seat as an Independent from inside a jail cell. He lost, but the fact that more than 27,000 people voted for a campaign run out of a prison may give some hope to Alaska Sen. Ted Stevens. The Republican isn't behind bars, but he was recently convicted of seven counts of failing to disclose hundreds of thousands of dollars in gifts.

Stevens calls his legal strife a "temporary situation," saying he has technically not been convicted because the judge has yet to hand down a sentence. A defiant Stevens vowed to appeal the jury's guilty verdict.

If a public display of audacity was the sole criteria to get out the vote in Alaska, Stevens would probably be a shoe-in on Tuesday. As it stands now, a Rasmussen poll conducted in late October had Stevens trailing Democrat Mark Begich by eight points.

Ohio, house of representatives

One of the most closely-watched House races in the U.S. on Tuesday night will be between Republican Steve Chabot, a seven-term congressman, and state representative Steve Driehaus in Ohio's 1st District. Chabot won the district two years ago by less than five percent. But this time, he's facing the "Obama effect" in a district that is more than a quarter black.

If national surveys turn out to be accurate and the African-American turnout is indeed significantly higher than it has been in the past, Driehaus could take the seat in a pivotal state that may be a harbinger of national results.

Kentucky, senate seat

In most election years, Republicans can count on Kentucky backing their congressional candidates. However, their reliance on the traditionally red state may not be a given this time, at least when it comes to the battle for its open senate seat. Senate Minority Leader Mitch McConnell's victory is far from certain there, with his Democratic rival Bruce Lunsford trailing by a mere four points.

McConnell's association with the Bush administration is making for a surprisingly close race. Kentucky's senate race is significant not only because Republicans usually don't face tough battles in the conservative state. It's also important because it could sideline a top GOP member.

If McConnell loses, the impact will be felt beyond the senate by a party that will be searching for seasoned leaders, if it's decimated on Nov. 4.