First on CBS News, Montana Gov. Steve Bullock spoke with political correspondent Ed O'Keefe Tuesday in his first one-on-one interview since announcing his candidacy for the 2020 Democratic presidential nomination. Watch the full interview in the video player above.

Montana Gov. Steve Bullock just became the 23rd Democratic candidate to enter the presidential race Tuesday, seeking to distinguish himself from the crowded field by highlighting his record as a Democratic governor in a state that voted overwhelmingly for President Trump in 2016.

"We need to defeat Donald Trump in 2020 and defeat the corrupt system that let's campaign money drown out the people's voice, so we can finally make good on the promise of a fair shot for everyone," Bullock said in a video announcement.

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In his first interview after announcing his run, Bullock told CBS News' Ed O'Keefe that he didn't see Mr. Trump as a good role model.

"I have plenty of policy disagreements with this president but also that the way that he conducts in the office and divides people, how he belittles people. That's not the example that you want out of a president. When we're expecting more from our preschoolers at times than a president, that's not the role model that I think most families want for their kids," said Bullock.

Asked about the ongoing trade dispute with China, Bullock said he considers the country "a tremendous economic threat" but criticized Mr. Trump's approach to trade.

"First of all, you don't just do it alone. America first shouldn't America alone, but you work with your allies and say that, 'Look, there's an expectation. If you're going to have access to my market, we'll have access on the same terms,'" Bullock said.

The Montana Democrat now joins the largest and most diverse Democratic primary field in modern history. Relatively unknown at the national level, Bullock must now compete with candidates like former Vice President Joe Biden and Sens. Bernie Sanders of Vermont; Elizabeth Warren of Massachusetts; and Kamala Harris of California.

Bullock has managed to win several statewide elections in predominantly rural Montana by running as a moderate who also embraces some liberal proposals. During the 2016 election, when Mr. Trump won Republican-leaning Montana by nearly 21 percentage points, Bullock was reelected by a 4-point margin.

On Tuesday the Montana governor launched his presidential campaign at his alma mater, Helena High School, before leaving for a three-day, eight-county swing through Iowa. It'll be his seventh trip to the first-in-the-nation caucus state. He has also visited early-voting states like New Hampshire and Nevada over the past several months.

Since assuming control of the governor's mansion in 2013, he has supported same-sex marriage, net neutrality and held pro-choice views on abortion. He also worked with the Republican-controlled legislature to push through some of the most sweeping campaign finance reforms in the country. Before his current tenure as governor, he served as Montana's attorney general for one term.

Bullock told O'Keefe that he's joining the packed field because he feels he can "make a meaningful difference."

"I want everybody to have the same opportunity that I had growing up and more and people don't have it. I think that I could add something."