Donald Trump is trying to defy convention yet again in the 2016 race for president -- this time, by winning an election in Wisconsin without the support of the state's influential conservative talk radio hosts.

Donald Trump
In this March 12, 2016, file photo, Republican presidential candidate, businessman Donald Trump speaks in Vandalia, Ohio. (AP Photo/Kiichiro Sato, File)

The Republican front-runner tried to lay some groundwork for his campaign in interviews Monday with three of the state's leading conservative talkers, including WTMJ radio's Charlie Sykes -- to whom Trump confessed on-air not knowing that Sykes is a leading voice against his candidacy. Two interviews later in the day didn't go much better.

It's fair to assume Wisconsin Gov. Scott Walker won't be announcing he's voting for Trump in the state's April 5 primary when the Milwaukee-based Sykes interviews the two-term Republican on Tuesday morning.

"It's remarkable how they drive the agenda in primaries," said Walker aide Stephan Thompson of Sykes and other conservative radio hosts in the state. "They are the biggest endorsement."

Walker would know.

He won the 2010 Republican primary for governor, and later the office itself, with support from Sykes and his unofficial counterpart in Milwaukee, WISN radio's Mark Belling.

That year, Walker beat Republican rival Mark Neumann overwhelmingly among voters within earshot of Sykes and others on the air in Milwaukee -- especially in the suburban counties that surround the state's largest city. That's the core of the metro area's conservative radio audience and home to almost half of the state's Republican voters.

Two years later, Sykes and other conservative hosts backed Mitt Romney in the state's Republican presidential primary. The former Massachusetts governor won by crushing former Pennsylvania Sen. Rick Santorum by more than 20 percentage points in the Milwaukee area.

Trump didn't appear all that ready for his round of talk radio interviews on Monday. For example, when asked about his past criticisms of Walker on Sykes' show, the billionaire businessman failed to mention that he donated $10,000 to Walker's re-election campaign in 2014.

The lack of preparation was notable given the importance of the state's 42 delegates. A solid win in Wisconsin by Texas Sen. Ted Cruz would likely require Trump to win the five remaining winner-take-all contests to avoid scrapping for the nomination at a contested national convention this summer.

Sykes in the morning and Belling in the afternoon -- both deeply critical of Trump and his candidacy -- have built a wide following in nearly 60 years combined behind the mic. They reach a metro Milwaukee audience of more than 500,000 people a day, according to their stations, and more among those living in the state's interior.

There are other conservative talk radio hosts at those stations, too, as well as other voices in pivotal parts of the state, including Jerry Bader in Green Bay and Vicki McKenna in Madison.

On Monday, Bader hammered Trump in an interview for his threats to file a lawsuit over how Louisiana selects its delegates to the Republican National Convention.

Trump went on to hang up on McKenna at the end of a combative interview, during which she challenged his incorrect assertions that Cruz's campaign was behind an ad campaign that featured a risque photo of his wife, Melania.

"There's just something about Wisconsin that's got just a really robust conservative talk radio infrastructure," said Collin Roth, managing editor of the conservative website Right Wisconsin, for which Sykes also writes.

Sykes endorsed Cruz last week and invited him to attend a conservative forum in GOP-heavy Waukesha County to Milwaukee's west. Sykes had long been a vocal opponent of Trump, a fact lost on the billionaire businessman when Sykes interviewed him by phone Monday morning.

"Before you called into my show, did you know I'm a hashtag Never Trump guy?" Sykes asked, referring to a Twitter designation for people united against Trump's candidacy.

"That, I did not know," Trump replied, even though it was Trump's staff that called to set up the interview.

Sykes had asked Trump earlier in the interview if he would apologize for indirectly mocking Cruz's wife. He was referring to Trump's retweeting last week of an unflattering image of Heidi Cruz.

"I didn't start it. He started it. If he hadn't started it, nothing would have happened," Trump replied.

"We're not on a playground. We're running for president of the United States," Sykes replied.

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