US media say President Joe Biden and former President Donald Trump are each certain to win their party's primary in Michigan on Tuesday.

Biden's Democratic party and the Republican party both held a primary in the Midwestern state for the November presidential election.

Media reports say that with 21 percent of the Republican vote counted, Trump has secured victory with 65.8 percent. Nikki Haley followed with 29.5 percent. Trump has beaten Haley in all of their contests so far, ramping up his advantage for winning the party's presidential nomination.

The reports say Biden also secured victory by winning 79.5 percent, with 17 percent of the Democratic vote counted. Lacking any major rival, he is expected to win the party's nomination in its national convention this summer.

But Biden also faced a protest vote in Michigan, home to a large Arab American population. Arab American voters are opposing Biden's policy over the conflict in the Gaza Strip, and called for marking the ballots "uncommitted." These votes have reached 14.9 percent and observers say the situation may affect Biden's re-election campaign.