With control of the U.S. Senate at stake, Democrats need to hold on to seats in states Donald Trump won in 2016. Sen. Claire McCaskill of Missouri holds one of these seats and is one of this year's most vulnerable senate Democrats.
The latest CBS News Battleground Tracker: Claire McCaskill with 45 percent and her Republican opponent Missouri Attorney General Josh Hawley at 45 percent among likely voters.
Missouri has been trending more Republican in recent in years, particularly when it comes to presidential politics. The Republican presidential candidate's winning margin has grown from one-tenth of a percentage point in 2008, to 10 points in 2012, and 19 points in 2016. McCaskill was first elected in 2006 as part of a blue wave when Democrats took control of both the House and the Senate.
Here are five things to watch in this race:
Is McCaskill too liberal for Missouri?
With the state's political leanings becoming more conservative, some voters may see McCaskill as out of step with Missouri now. Fifty-five percent of Missouri voters say she is about liberal as most congressional Democrats. Just a quarter see her as more moderate. McCaskill's re-election prospects hang in part on her ability to on to these moderate and independent voters that helped boost her in the past.
The Trump factor
Most Missouri voters (68 percent) say President Trump will be a factor in their vote. For Republicans it will be to support him, and for Democrats to oppose him. Mr. Trump endorsed Republican Hawley early on in the campaign. At 50 percent, the president's job approval here is higher than it is nationally. If those voters who came out for Mr. Trump in 2016 show up in 2018, it's likely to be good for Hawley.
The gender gap
McCaskill got strong backing from women in her 2012 reelection bid when her Republican opponent, Todd Akin, made his infamous "legitimate rape" remark. She won women by 22 points, up from 6 points in 2006. But with Trump's decisive victory here, he won the support of both women (+10 points) and men (+30 points). Hawley will need to peel off some women voters from McCaskill, and keep his margins up among men. McCaskill will look to continue her strong performance with women. In the latest Battleground Tracker, 13 percent of women who say they voted for Trump are backing McCaskill. McCaskill hopes to persuade more Trump supporters to back her and turn out some new voters who don't typically vote in midterms.
McCaskill has gone after Hawley for his lawsuit, as the state's attorney general, against the Affordable Care Act. Hawley has countered saying he wants to repeal Obamacare but maintain coverage of pre-existing conditions. Voters see McCaskill (41 percent) as better than Hawley (33 percent) on the issue of health care, according to CBS News polling. Will this be the issue that's on the minds of voters when Election Day comes? Trade and tariffs are also an in the state.
Education and Race
Some of Trump's strongest supporters in 2016 were white voters without a college degree and that was no different in Missouri. Seven in 10 of these voters supported him, many living in rural areas. McCaskill has appealed to some of these voters in the past. While not winning a majority, about four in 10 of whites without a degree backed McCaskill in 2012 and 2006. She can't afford to lose too many of these voters, and at the same time, Hawley is looking to perform better with this group than McCaskill's past Republican opponents have. Nine in 10 black voters backed McCaskill in her previous elections, but black voters made up a slightly smaller share of the state's electorate in 2016 (14 percent) than they did in 2012 (16 percent), and an even smaller share in 2010 (13 percent), which was a midterm election. McCaskill hopes to drive up turnout among black voters.