Voters in Arizona, Florida and Oklahoma head to the polls in the final multistate elections of the 2018 primary season. They offer another test of President Donald Trump's imprint on the Republican Party. But the races, especially in Arizona, will take on special meaning following the death of Sen. John McCain, which has spurred a debate about how far the party has moved to the right since his failed 2008 bid for the presidency.

What to watch:

TRUMP, McCAIN AND A TOSSUP SENATE SEAT

Perhaps no other race in the country demonstrates the competing strains on the modern Republican Party than the t...