Sen. Ron Johnson on the GOP situation: "I think things remain reasonably uncertain." | AP When support for Trump is not an endorsement Sen. Ron Johnson draws the distinction in discussing Donald Trump.

Locked in a tough fight for reelection this November, Sen. Ron Johnson said Sunday he plans to support Donald Trump for president but didn't formally endorse the presumptive nominee.

There’s a big difference between the two, the Wisconsin senator explained on CNN’s “State of the Union” after saying he intends "to support the Republican nominee."


“Well to me," he told Dana Bash, "endorsement is a big embrace. It basically shows that I pretty well agree with an individual on almost everything,” Johnson said. “That's not necessarily be the case with our nominee, so I’ll certainly be an independent voice where I disagree with a particular nominee. I'll voice it, whether it's Hillary Clinton, Donald Trump, or anybody else.”

Trump’s controversial candidacy could spell trouble for Johnson this fall, who faces a stiff challenge from former Sen. Russ Feingold, whom Johnson ousted in 2010. A recent Marquette University Law School poll shows Johnson trailing Feingold, 51 percent to 42 percent, among likely Wisconsin voters.

Johnson was not willing to dismiss the notion that Trump’s nomination might come undone at the Republican National Convention in Cleveland even though Trump would seem to have more than enough delegates. He said that while he’s not a part of any movement to deny Trump the GOP nomination, “nobody can really predict what's going to be the outcome of our nomination process.”

He also made that point about unpredictability in discussing his support for Trump: "It has been my intention to support the Republican nominee. And again nobody can predict the outcome of this thing. So I think things remain reasonably uncertain."