JEFFERSON CITY, Mo. (AP) — The Latest on the primary election in Missouri (all times local):

4:30 p.m.

Missouri voters are casting votes to select the nominees in one of the most contentious U.S. Senate races in the nation.

Patricia Green, a 70-year-old retired Columbia resident, said she came to the polls Tuesday to support Democratic U.S. Sen. Claire McCaskill and said she wants to volunteer for her campaign.

Green said McCaskill is "about as good as a Democrat can get" and praised her as a good balance to the Republican control of the Missouri governor's office and state House and Senate.

Green said she doesn't know if President Donald Trump's endorsement is good or bad for Missouri Attorney General Josh Hawley, McCaskill's likely GOP opponent in November. She called Trump "unraveled."

Republican Jay Kirschbaum is a 60-year-old employee benefits consultant from Chesterfield, voted for Hawley because he said he is the Republican most likely to beat McCaskill. Kirschbaum said he was most upset by McCaskill's support of the Affordable Care Act, which he contends caused medical costs to go up.

Kirschbaum called Trump's record on the economy and courts "stellar."

3:45 p.m.

Voters heading to the polls in Missouri are deciding whether to make Missouri a right-to-work state or to toss out the law banning mandatory union dues.

Glenn Powers is a 65-year-old government worker for St. Louis County who says he voted "no" on the right-to-work proposal. Powers says he supports labor and equity and is worried about the hollowing out of the middle class.

Gilmore Stone is a 54-year-old Republican from Columbia who works in manufacturing. He says he supports right to work. Stone said workers should not be required to pay into organizations that aren't directly connected to their employment and that he supports giving workers the choice to pay dues.

If voters consent, Missouri would become the 28th state outlawing mandatory union fees in workplace contracts and the sixth Republican-led state to do so in the past six years.

12 a.m.

Missouri voters are expected to set up one of the nation's most contentious Senate races, with Democratic incumbent Claire McCaskill and Republican Josh Hawley considered heavy favorites in the primary.

McCaskill's hopes of winning a third term in the Republican-dominated state could depend both on convincing voters she's sufficiently moderate and how voters feel about President Donald Trump, who is backing Hawley. Trump coasted to a 19-percentage point victory in the onetime bellwether state less than two years ago, which is why Republicans consider McCaskill one of their top targets nationwide this fall.

Voters also will get a chance Tuesday to decide whether to make Missouri a right-to-work state or to toss out the law banning mandatory union dues and pick nominees in numerous House races.