U.S. Senator Mary Landrieu with supporters during a "Women with Mary" campaign event on Oct. 22, 2014 in New Orleans, La.
Sean Gardner/Getty

Nail-biters: The 8 closest races across the US

Updated

With less than two weeks before Election Day, it’s crunch time for candidates, who are ramping up travel schedules, making last-minute fundraising pleas, churning out attack ads and trying to get one last leg up in their final debates.

The Republicans are expected to remain comfortably in control of the House of Representatives and could even pick up a few seats, but the battle for the Democratic-held Senate  is still very much up in the air. Several governors’ races are heating up as well, with some incumbents looking like they are in big trouble – especially in presidential battleground states.

We received lots of input from the msnbc.com community on which races you’re paying  particularly close attention to. Below is a look at some of the tightest and most interesting races across the country.

We want to hear from you! For the next piece in our series, we’re looking at the best one-liners and comebacks used by candidates this election cycle. What has jumped out to you? Leave a comment on this post to submit your suggestions!

Colorado: Mark Udall vs. Cory Gardner

This Senate race could also be a nail-biter. According to the RealClearPolitics average of polling data surrounding the race, GOP Rep. Cory Gardner has a narrow, 3.8 point lead ahead of one-term incumbent Democratic Sen. Mark Udall. But Udall has a significant fundraising advantage, which could help him in the final weeks of the campaign.

Udall is stressing his support for abortion rights and contraception in hopes of winning over young, single women who often don’t vote in midterm elections. He has gone after Gardner’s past support for “personhood” legislation, which would restrict access to certain types of birth control. Udall has even been nicknamed “Mark Uterus” because of his focus on women’s rights. Republicans, in turn, are trying to tie Udall to Obama, who is unpopular in the state. Gardner has repeatedly attacked Udall for voting for Obamacare.

Florida: Rick Scott vs. Charlie Crist

Former Sunshine State Gov. Charlie Crist is gunning for his old job against incumbent Republican Gov. Rick Scott. While there was no bizarre bickering Tuesday over a fan, Crist – a Republican turned Democrat – and Scott traded blows regarding their personal wealth in their final debate. Crist tried to paint Scott as an out-of-touch businessman who travels in a private jet and lives in an ocean-front mansion. Scott, in turn, said Crist “grew up with money … I grew up with a family that struggled.” The back-and-forth centered on calls to increase the minimum wage to $10.10, which Crist wants but Scott is against.

The two fought fiercely over several other issues, including the economy, immigration, medical marijuana and state executions. A Quinnipiac University poll released Wednesday showed the race deadlocked, with both getting 42% of the vote. Crist may have a slight advantage because he has a small lead among independents, 41% to Scott’s 38%.

Georgia: Michelle Nunn vs. David Perdue

Republican David Perdue and Democrat Michelle Nunn—daughter of former Sen. Sam Nunn—are in a tight race for retiring GOP Sen. Saxby Chambliss’ seat.

Nunn polled well at the start of the election cycle but has since fallen behind with several surveys showing the two candidates neck and neck. Like Louisiana, if no candidate gets 50% of the vote, there would be a Jan. 6 runoff election. Libertarian Party candidate Amanda Swafford has also been picking up about 4% to 5% support and could force a runoff if she picks off votes from Perdue.

Nunn has had major star power on the campaign trail, with both former President Bill Clinton and first lady Michelle Obama stumping for her.

Iowa: Bruce Braley vs. Joni Ernst

Democrats are in danger of losing this Senate seat long held by retiring Sen. Tom Harkin. The race has been very close throughout the election cycle, but recent polls show Republican Joni Ernst with a slim lead – ranging from 2 to 4 points and often in the survey’s margin of error – against Democratic Rep. Bruce Braley.

Among other things, Republicans have been trying to take advantage of a soundbite in which Braley—once considered a shoo-in to win the race – called the state’s senior senator, Republican Chuck Grassley, a “farmer” who lacks credentials to become chair of the Senate Judiciary Committee. Democrats, meanwhile, are trying to depict Ernst, a state senator and military veteran popular with tea party supporters, as being too conservative in the state, especially on issues like reproductive rights, minimum wage and climate change.

Ernt – who was propelled into the national spotlight this spring with an ad saying she’s uniquely qualified to cut spending in Washington because she grew up castrating hogs on an Iowa farm – is out with a new ad featuring, yes, pigs.

Kansas: Pat Roberts vs. Greg Orman

Kansas voters have not elected a Democrat to the Senate since the 1930s. That could change on Nov. 4 in this race that’s considered a tossup.

This Senate race has thrown a curve ball into both parties’ plans. Democratic candidate Chad Taylor dropped out of the competition in September, leaving incumbent Republican Sen. Pat Roberts trying to secure a fourth term against independent candidate Greg Orman.

Roberts has been in trouble for quite some time, narrowly beating out tea party challenger Milton Wolf in the state’s GOP primary. What makes the race even more of a wild card is that Orman has said he isn’t sure which party he’s going to caucus with.

Roberts has tried to tie Orman to President Obama, who remains unpopular in the state. Orman, meanwhile, is trying to pitch himself as an independent voice that is much needed on Capitol Hill.

Louisiana: Mary Landrieu vs. Bill Cassidy vs. Rob Maness

Chances are, the Senate race in Louisiana will not be decided on Nov. 4. Democratic Sen. Mary Landrieu is being challenged for a fourth term by Republican Rep. Bill Cassidy and tea party favorite Rob Maness. While polls have consistently showed Landrieu with a lead against Cassidy, she’s not near the 50% threshold required by the state to avoid a runoff election between the top two candidates.

Right now, the GOP vote is being divided by Cassidy and Maness. But if Landrieu is forced into a runoff between just her and Cassidy, polls show the sitting senator could lose. The likely Dec. 6 runoff is expected to be brutal, especially if the outcome will determine which party controls the Senate.

Republicans have aired ads skewering Landrieu’s support for Obamacare. Landrieu, meanwhile, is trying to distance herself from Obama’s energy and health care policies.

New Hampshire: Jeanne Shaheen vs. Scott Brown

Republican Scott Brown, a former Massachusetts senator, hopes to unseat Democratic incumbent Sen. Jeanne Shaheen in this state, which holds the first-in-the-nation primary. Brown has trailed consistently this election cycle but recent surveys indicate he’s closing the gap.

Brown, defeated as Massachusetts senator in 2012 by Elizabeth Warren, has been trying to tie Shaheen to Obama’s positions on health care, immigration and foreign policy as the president remains unpopular in the state. Shaheen, in turn, has accused Brown of being a carpetbagger and has called him a protector of big oil companies.

The two squared off Tuesday in a debate where two national issues – the Ebola crisis and the rise of ISIS – took center stage. Shaheen repeatedly accused Brown of using scare tactics following Brown’s recent declaration that it would be “naïve” not to consider that Ebola-infected terrorists could enter through the country’s southern border.

Wisconsin: Scott Walker vs. Mary Burke

Recent polls are showing Republican incumbent Gov. Scott Walker and Democratic challenger Mary Burke also in a dead heat. The stakes are high, especially for Walker, who survived a recall election in 2012 and is considered a potential 2016 presidential candidate.

Walker and Burke, a businesswoman and former Wisconsin commerce secretary, both played it safe during their final debate on Friday, sticking to state and local issues and shying away from more controversial ones – like collective bargaining power, the minimum wage and reproductive rights – that have fiercely divided the electorate. 

Bruce Braley, Charlie Crist, Colorado, David Perdue, Florida, Georgia, Iowa, Jeanne Shaheen, Joni Ernst, Kansas, Louisiana, Mary Landrieu, Michelle Nunn, New Hampshire, Rick Scott, Scott Brown, Scott Walker and Wisconsin

Nail-biters: The 8 closest races across the US

Updated