CLEVELAND — Sen. Ron Johnson delivered a blistering speech Tuesday at the Republican National Convention, accusing Democrats of lacking the policy vision necessary to keep America safe and defeat ISIS.     

The most notable news from the Wisconsin senator’s address, however, might be the fact he was making it at all. Johnson had a change of heart over the weekend, his campaign said, after a personal invitation from Republican National Committee Chairman Reince Priebus — despite the apparent danger of associating with the party’s now-official presidential nominee, Donald Trump.  

The turnabout was a bold step for Johnson. It threw into stark relief the dramatically different approach he and his campaign are taking to Trump than another vulnerable senator in a neighboring state: Illinois Sen. Mark Kirk.  

They’re both first-term lawmakers who ran elections in the tea-party wave of 2010 but are running for re-election in states that have turned blue in every presidential election since the end of the 1980s. They’re widely seen as the two GOP incumbents most likely to lose their re-election (though Kirk is regarded as the more vulnerable).  

And yet, while Johnson speaks at the RNC, Kirk is back home in Illinois. While Johnson says he wants to “focus on areas of agreement” (as his campaign put it recently) with Trump, Kirk loudly withdrew his support earlier this year from the GOP’s new leader.  

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“I think he’s too bigoted and racist for the Land of Lincoln,” Kirk said of Trump earlier this year. The divergent approaches from Johnson and Kirk reflect the differing theories within the GOP over how best to handle Trump, whose penchant for provocation and deep unpopularity have made him a real dilemma for down-ballot Republicans.  

Republicans like Kirk believe that running away from him is the only way to survive an Election Day in a blue state, convinced that moderate voters will only vote for them if they disavow Trump.  

But other Republicans, Johnson included, while not exactly bear-hugging Trump, have decided not to run from him either.    

Johnson has reprimanded Trump in the past, over his proposed ban on Muslim immigration and racially-based criticism of Federal Judge Gonzalo Curiel.   

Though the Johnson campaign believes Trump may not be a net positive, he could help Republicans electorally in at least some ways — or so the thinking goes.  

“What we also know is Trump helps in the north and northwest, bringing people out of the woodwork, and hurts in the southeast with the base,” said one Wisconsin Republican familiar with the campaign. “They love Ron, and our ground game will turn them out.”  

Two senators — two very different approaches.