Gov. Chris Christie said he knew he would upset allies and other Republicans by endorsing Donald Trump for president.

“I went into this with my eyes wide open. I knew it would make some people upset,” Christie said Monday on “Ask The Governor.”

“I think Donald Trump’s the best guy, and I’m not an on-the-sidelines guy. I’m not going to be one of these people who sits on the side and snipes,” Christie said.

Christie didn’t rule out accepting the vice presidential nomination as Trump’s running mate but said he’d discuss that with his wife, Mary Pat, only. He said he wasn’t promised anything.

“No one campaigns for vice president. That’s not what you do,” Christie said.

Christie will campaign for Trump on Tuesday in Ohio and Kentucky. He said his profile will mean he has Trump’s ear in policy discussions going forward.

“I am the highest-level endorser that Donald Trump has had. I’m the person with the most experience in government that is in his circle. So as a result, that gives me some credibility to make recommendations and suggestions over time, when appropriate, for him to consider,” Christie said.

“I’m not the adult in the room. I’m one of the adults in the room,” he said.

Christie said the choice came down to selecting the candidate who can beat Hillary Clinton, the leading Democratic contender.

“I think she is wholly, wholly inappropriate to be president of the United States. Donald Trump has won three of the first four primaries. I’ve known him for 14 years. He will probably win at least seven or eight of the 11 primaries, if not more, tomorrow night. He’s going to be the Republican nominee for president. And I want to make sure Hillary Clinton doesn’t win.”

Asked about his past criticisms of Trump, Christie said that’s part of campaigning. He said George H.W. Bush called Ronald Reagan’s economic plan “voo-doo economics,” then was his vice president. He said Joe Biden ran in the 2008 primaries against Barack Obama, then became his vice president.

“When we believe we’re the best person, we aggressively make the best case we can for ourselves and against others. And it doesn’t mean I believe with Donald Trump on every issue, because I don’t.”

Christie said he doesn’t have the same concerns about Trump as people who only know him from television.

“I’ve known Donald for 14 years, so I don’t have some of concerns personally that some people have that don’t know him all that well,” Christie said.