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With a dramatic and historic presidential election dominating headlines, Americans could be forgiven for focusing on that race over the hundreds of other federal contests also taking place Nov. 8. But as Election Day nears, that laser focus will likely soften. Voters will be inundated with campaign pamphlets and attack ads addressing down-ballot races.

Many Republicans, for example, are focusing their efforts on House and Senate races in hopes of maintaining their majorities there. Indeed, GOP donors who soured on Donald Trump are giving large sums to conservative super PACs and outside groups that are pouring money into various congressional races.

As the calendar moves closer to the election, InsideGov, a politics research site powered by Graphiq, wanted to examine the most competitive Senate races this cycle. It used data from the Cook Political Report to find the top Senate races to look out for in 2016.

Florida

The Sunshine State often features expensive, closely watched contests, and that’s especially true in presidential years. Florida’s 29 Electoral College votes make it one of the biggest gets in the race for the White House, meaning the state receives lots of attention from big-name politicos. And that’s only magnified this year since its Senate race features one of the best-known names in GOP politics.

After a failed attempt at the Republican presidential nomination this year, Florida Sen. Marco Rubio reversed an earlier decision to retire from the Senate. He announced he would run for re-election in his home state in June, and cruised to an easy primary win on Aug. 30.

Democratic Rep. Patrick Murphy also easily won his primary, but that was largely because he didn’t have a strong opponent in fellow Democratic Rep. Alan Grayson. Murphy has faced questions for months about his résumé and previous work experience, and Rubio’s campaign has started to weave those questions into TV ads against Murphy.

Rubio holds about a 6-point lead in the polls, according to averages from RealClearPolitics. Expect the race to remain close and competitive until voters head to the polls in November.

Nevada

After spending the last 33 years representing Nevada on Capitol Hill, Sen. Harry Reid is hanging up his hat. The Democrat announced his retirement in March 2015, setting the stage for a highly anticipated open-seat race.

Democratic candidate Catherine Cortez Masto, the state’s former attorney general, has raised more than $8.7 million for her campaign. Her Republican challenger, Rep. Joe Heck, has collected close to $7.5 million (fundraising figures reflect data as of June 30, the latest available).

Outside groups are also getting in on the action, dropping millions on ads for and against their preferred candidates. According to the Las Vegas Sun, the Democrat-aligned group Senate Majority PAC spent about $870,000 on anti-Heck ads, while Freedom Partners Action Fund cut a check for a $1.2 million ad buy against Cortez Masto. Freedom Partners Action Fund, a conservative group backed by the Koch brothers, was founded in 2014 in the midst of that year’s midterm elections. The group doled out more than $25 million in the last election, and has already spent upwards of $17 million in 2016, according to the latest data available.

North Carolina

Like Nevada, North Carolina has become more of a purple state in recent years, a fairly even mix of Republican red and Democratic blue. But the unpopularity of the two Republicans at the top of the ticket in North Carolina — presidential candidate Trump and Gov. Pat McCrory — threaten to sink the chances of Sen. Richard Burr.

Republicans in the Tar Heel State have a complicating factor this year in HB2, the so-called bathroom bill that became law in March. It requires that people use the bathroom or changing area that corresponds to the sex listed on their birth certificate. It directly impacts transgender people, whose gender identity might be different from what appears on their birth certificate.

The law has generated a steady drumbeat of headlines and negative publicity. McCrory has repeatedly defended the law. Polling averages from RealClearPolitics show McCrory has been down in the polls since early July.

For his part, Burr, hoping to nab his third term in the Senate, holds a 3.3-point polling advantage over Deborah Ross. Democrats are eyeing this closer-than-expected race with hopes of recapturing some of the magic from 2008, when President Obama won the state and former Sen. Kay Hagan became the first Democrat to win the seat since 1972. A super PAC backing Hillary Clinton’s presidential run recently made a significant ad buy in a handful of states including North Carolina. And a conservative group just spent $1 million on air time for a pro-Burr ad.

Pennsylvania

Freshman Sen. Pat Toomey narrowly won his seat in 2010, besting his Democratic opponent, former Rep. Joe Sestak, by just 80,229 votes. Toomey’s 2016 race looks to be another nail-biter, with current polling revealing a single-digit, see-sawing race.

Like many other Republicans this year, Toomey’s campaign has struggled with how to approach Trump’s candidacy. Toomey came out against some of Trump’s more controversial comments and didn’t attend the Republican National Convention in nearby Cleveland, but hasn’t officially come out against the businessman. But the Democrat in the race, Katie McGinty, has pressured Toomey to articulate where exactly he stands on Trump.

Campaigns and outside groups are funneling millions of dollars into the state on television ads about the race. Bloomberg reported that about $31.8 million has been spent — so far — on television ads in the state.

New Hampshire

A political hotspot earlier this year due to the presidential primaries, the Granite State continues to be a hub of activity since it features one of the closest Senate races in the country. Republican Sen. Kelly Ayotte currently holds a razor-thin lead in the polls over her Democratic challenger, Gov. Maggie Hassan.

Both are popular politicians. Hassan is serving her second term as governor, and has held various state-level positions since 2004. Ayotte is looking for her second term on Capitol Hill, and has been considered somewhat of a rising star within the GOP.

But Ayotte, like many other Republicans, walks a fine line in regard to Trump. She has said she would vote for her party’s presidential nominee, but hasn’t officially endorsed Trump. In mid-August, she said she would reconsider that vote if necessary. “For every person you vote for, essentially you’re always going to leave open the opportunity to reevaluate,” Ayotte said. “How could I not say that about any situation?”

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