LANSING, Michigan — Presidents Biden and Trump easily won their party’s primaries in Michigan, but Tuesday’s results showed that both candidates have cause for concern in their bid to win the swing state in November.

An “uncommitted” vote in Michigan’s Democratic primary was the first indication of how backlash over Mr. Biden’s handling of the Israel-Hamas war in Gaza might impact his reelection campaign. 

Mr. Trump won his primary by a large margin, but support for his rival, Governor Haley, once again showed that some Republican voters may have misgivings about giving the former president another four years in the general election.

Michigan was the last major primary state before Super Tuesday, and both sides were watching closely for implications for the November general election in one of the few genuine swing states left in the country.

Mr. Biden has now cruised to victories over lesser known candidates in South Carolina, Nevada and New Hampshire, which he won in a write-in campaign. Tuesday’s results show that his standing is still strong in Michigan, which Mr. Biden returned to the Democratic column in 2020.

Mr. Trump has swept all five of the early state contests, including South Carolina, the home state of rival Mrs. Haley. He now heads into Super Tuesday, when 15 states and one territory hold Republican nominating contests, as the overwhelming favorite to lock up the Republican nomination.

Michigan was one of three so-called blue wall states, including Wisconsin and Pennsylvania, that Mr. Trump won in 2016. He predicted a big win beforehand.

Just 16 of Michigan’s 55 Republican presidential delegates will be determined by the primary results, while the remaining delegates will be allocated during a March 2 convention. 

Mr. Trump’s anticipated dominance at the state convention, where grassroots activists will play a key role, will decide the allocation of the remaining 39 GOP delegates.

Michigan, has the largest concentration of Arab Americans in the nation, has become the focal point of Democratic frustration regarding the White House’s actions in the Israel-Hamas conflict. 

That anger came through loud and clear on Tuesday as some voters marked “uncommitted” on their ballot in the Democratic primary. Mr. Biden still dominated the primary, but the result could be a concern in a state he won by less than 3 percent in 2020 and likely can’t afford to lose this year.

Despite Trump’s clear victory in Michigan, Mrs. Haley still saw significant support from the swing state’s Republicans.

Some of her best results came in Oakland and Kent counties, where Democrats have been gaining ground in recent years, contributing to their recent statewide success. She also performed better in counties where the state’s largest universities are located, Washtenaw and Ingham counties.

Mr. Trump has dominated in primaries with help from his base but his strength among general election voters remains unclear. The former president has appeared in Michigan regularly in the eight years since he became president, while Mrs. Haley only began stumping in the state over the weekend.

AP VoteCast reveals that a large portion of Mr. Trump’s opposition within the Republican primaries has come from voters who abandoned him before this year.

All three statewide Republican candidates that Mr. Trump endorsed in the 2022 midterms were crushed by Democratic incumbents.