GREEN BAY, Wis. — After months of dominating the Republican race, Donald Trump has endured one of his worst weeks since launching his presidential bid, and while he remains the GOP front-runner, his struggles have underscored his weaknesses and increased the possibility that he might fall short of seizing the nomination.

The bad news piled up quickly for Trump: his campaign manager charged with misdemeanor battery for grabbing a female reporter's arm, a series of interviews with conservative talk radio hosts who pummeled him, a highly regarded poll showing him trailing badly in advance of Wisconsin's primary next week, and, finally, Wednesday's fracas over his stand on abortion.

All of those developments deepened existing doubts about Trump. Many Republican strategists worry about his staggering level of unpopularity with female voters, which was highlighted by the battery charge against campaign manager Corey Lewandowski and Trump's comment during a town hall suggesting women should face “some sort of punishment” for getting abortions if they were made illegal.

Trump has said his comment was taken out of context.

In an interview Thursday with Fox News Channel's “The O'Reilly Factor,” Trump blamed the flub on a “convoluted” interview.

“This was a long, convoluted question,” he said. “This was a long discussion and they just cut it out.”

Trump insisted he's always believed abortion providers, not women, should be held responsible for performing illegal abortions.

Nevertheless, those sorts of stumbles, as well as Trump's calls to talk show hosts whose opposition to him he seemed unaware of, raised questions about whether he is capable of building and running a campaign operation that can win a general election, political operatives said.

“You're seeing a campaign that's making it up as they go along every day. That's deadly,” said John Brabender, a chief strategist for former Sen. Rick Santorum's campaign who is now neutral in the race.

Trump's “renegade campaign” and defiance of political norms “served them fine in the early phases,” Brabender said. Now, however, it's “hurting Trump a great deal.”

The problems come at a contradictory point in the campaign for Trump. He has defeated one rival after another. But he continues to draw support from only a minority of Republican voters. That contrasts with front-runners in previous presidential contests who had begun pulling away from rivals by this point in their campaigns.

Of course, Trump has proved skeptics wrong before, demonstrating a hold on his supporters that has defied conventional political judgment. Part of what may make this rough patch different is the Wisconsin polling.

Based simply on its demographics — with a large number of blue-collar GOP voters and an average number of conservative, evangelical Christians — Wisconsin would have seemed to be a much better fit for Trump than for his chief rival, Ted Cruz. The Texas senator has relied heavily on religious conservatives for his victories so far.

Instead, Trump trailed Cruz by 10 percentage points in the poll released Wednesday by Marquette Law School, which has a strong track record for accurately forecasting the state's elections.

If the poll forecast holds up, it could be enough for Cruz to sweep the state's 42 delegates under the “winner-take-most” rules of Wisconsin's GOP primary. That would be a setback for Trump, who is barely on track to win the 1,237 delegates needed to avoid a contested convention when Republicans meet this summer in Cleveland. His campaign aides did not respond to requests for comment.

The next round of primaries after Wisconsin could be kinder to Trump, particularly in his home state of New York. Still, he has yet to win more than 50 percent of the vote in any of the 31 states that have held GOP primaries or caucuses.

David Lauter reported from Washington and Michael Finnegan from Green Bay. Chris Megerian in Appleton, Wis., Evan Halper in Purchase, N.Y., and Associated Press contributed.

dlauter@tribune.com