What to watch in Tuesday's primaries as Graham Platner tries to clinch Senate nomination in Maine

Graham Platner, Democratic candidate for U.S. Senate, speaks at a campaign event Friday, June 5, 2026, in Bar Harbor, Maine. (AP Photo/Robert F. Bukaty)

WASHINGTON (AP) — Voters across Maine, Nevada, South Carolina and North Dakota head to the polls Tuesday for another day of primary elections in America, but much of the political world will be focused on Maine’s high-stakes U.S. Senate contest.

The results are not in question. Neither Republican incumbent Sen. Susan Collins nor Democratic challenger Graham Platner faces serious opposition for their party’s nomination. And yet Tuesday marks an especially significant moment for Platner, the embattled veteran and oyster farmer, who is fighting to rebuild his credibility in a campaign rocked by controversy.

Elsewhere, President Donald Trump’s clout within his party will be tested anew in states like South Carolina and Nevada, where he’s endorsed his favored candidates. Democrats hope to build momentum in Nevada in their broader push to reclaim key governor’s seats.