Transcript for Voters in 4 states go to the polls in high-stakes primaries
and move on to politics. Voters going to the polls in Ohio, North Carolina, Indiana, West Virginia, all setting the stage for November's midterms with control of the house and senate at stake and our senior congressional correspondent Mary Bruce is tracking it all. Good morning. Reporter: All eyes on west Virginia and the controversial former coal baron turned senate candidate don Blankenship. President trump coming out and urging voters to the to back Blankenship, a member of his own party, Republicans are afraid in Blankenship wins the nomination today he won't be able to Stange up to the Democrat come November and they'll lose the cancer to turn this blue state red. He's the GOP senate candidate that has his own party on edge. I'm neither despicable or a moron or a bigot. Reporter: As West Virginia voters head to the poll president trump is urging them not to back don Blankenship. Tweeting Blankenship can't win the general election in your state, no way. Remember Alabama. Blankenship responded saying he's trumpier than trump and pointing out that the president supported accused pedophile Roy Moore. We all really liked president trump's policies but we know that he doesn't get things right. Reporter: Blankenship has been going after the Washington establishment but sparked outrage with this racial remark about the family of Mitch Mcconnell's wife Elaine Chao. Mitch Mcconnell creates millions of jobs for China people. Reporter: Blankenship served a year in press ton for a mine safety conviction after a 2010 explosion in one of his mines killed 29 people. But he recently told us he did fog wrong and insists he's misunderstood. I'm probably the most honest person that ever ran for office. Reporter: Now, George, Blankenship has been embracing the president throughout this incredibly tight race and now he claims trump is simply being misinformed by the Washington sustainment and Republican leaders on the hill who Blankenship says doesn't want him to win because he'll help promote the president's agenda. So iortant for Republicans because you've got in Ohio, Indiana, West Virginia, Democrats on defense if the Republicans can pick up one of these seats, it helps secure senate control for them. Reporter: Exactly. Republicans see these key races today as their best chance to grow their senate majority. They're looking to nominate Republican candidates these red states that voted for Donald Trump but where there are currently democratic incumbent, keep a very close eye on Ohio and Indiana where you see the Republican candidates scrambling to out-trump each other. In Indiana one has been carrying a cardboard cutout off the president just to see who is lose to the president than anybody else. Mary, thanks very much. Michael.
This transcript has been automatically generated and may not be 100% accurate.