Less than five months remain before the United States holds its midterm elections, which are key to determining control of Congress — and the success of President Donald Trump’s final two years in office.Primaries are currently under way to determine which candidates will represent their political parties in the final round of voting.Recommended Stories list of 3 itemslist 1 of 3Platner wins Maine Democratic Senate primary, vows to oust Collinslist 2 of 3Georgia Republican primary delivers mixed results for Trumplist 3 of 3US progressive Lewis George on track to become DC mayor after Trump threatsend of listOn Tuesday, three more states will head to the polls for primary races: Utah, Maryland and New York.Joining them for a run-off election will be South Carolina, which saw several of its June 9 primary races result in a split field, with no single candidate receiving a majority of 50 percent or more.As a result, the top two candidates in those races are headed to a showdown on Tuesday to determine who will advance to November’s midterms.What are the biggest races to follow this week? Here’s a breakdown of some of the nail-biters.Ben McAdams was the last Democrat to represent Utah in Congress, and he’s running again in this Tuesday’s primary [File: Rick Bowmer/AP Photo]In Utah, a potential breakthrough for Democrats