Biden and Trump cruised in Tuesday’s primaries. But both showed signs of weakness.

President Joe Biden and former President Donald Trump are still staring down significant segments of their electoral bases who aren’t on board.

The holdouts in each party continued to flex their muscles on Tuesday in primaries in New York, Wisconsin, Connecticut and Rhode Island. And though there were more Republican holdouts — voters who cast ballots for candidates other than Trump — than Democratic ones in those contests, Biden’s problem still seemed more acute.

That’s because the Trump holdouts were concentrated in places Republicans have already lost — and will not come into play in November — while the “uncommitted” protest vote against Biden was strongest among Democrats’ core base.

Tuesday’s primaries, while wholly uncompetitive, were an opportunity for Biden to shore up that base. Democratic voters in Connecticut and Rhode Island, where “uncommitted” was on the ballot, aren’t especially progressive, which would typically favor Biden. And Wisconsin, which had an “uninstructed delegation” ballot line, is a key general election swing state.

But Biden showed signs of weakness in all of those states. In Connecticut and Rhode Island, “uncommitted” broke 10 percent, while “uninstructed” registered just slightly below that mark in Wisconsin.

The anti-Biden Democratic vote on Tuesday was concentrated in predictable places: cities with a significant college presence like New Haven, Connecticut (where “uncommitted” got 24 percent), Providence, Rhode Island (29 percent), and Madison, Wisconsin (“uninstructed” even tied Biden in one precinct and got 15 percent overall in Dane County).

College towns like Madison have become a Democratic salve in swing states in recent elections, and Biden can’t afford resistance there.

But that doesn’t mean Trump doesn’t have problems with some traditional Republicans, especially in the suburbs. Nikki Haley dropped out of the Republican presidential primary four weeks ago but still got 27 percent of the vote in upscale Westport, Connecticut, and 22 percent in Greenwich, Connecticut. In the so-called WOW counties around Milwaukee — the lynchpin of Republicans’ Wisconsin victories — Haley got 17 percent in Ozaukee, 14 percent in Waukesha and 12 percent in Washington.

That trend continued in New York, which also held its presidential primaries on Tuesday. Haley broke 20 percent in three counties: Monroe, home to Rochester (25 percent), Tompkins, home to the college town of Ithaca (24 percent) and Manhattan (22 percent).

New York didn’t have an “uncommitted” option, and the blank ballots that organizers encouraged Democratic voters upset with Biden over the Middle East to submit won’t be tallied until the results are certified in the coming weeks. So it’s too early to know whether a significant protest vote existed there.

Primaries aren’t general elections, and many voters will undoubtedly come home to their party by November. But both Biden and Trump have significant work to do before then to improve their standing with their bases.

And it’s Biden who needs to make up more ground. Trump, after all, is leading in the polls — in six of the seven general election swing states, according to new polling from The Wall Street Journal released Tuesday night.