The former Massachusetts governor Deval Patrick has entered the race for the Democratic presidential nomination to take on Donald Trump next year.

Patrick, who said in 2018 he would not run, had indicated the announcement was coming. A YouTube video was duly released early on Thursday morning with the campaign slogan “Deval for all”.

“You can’t know if you can break through unless you get out and try,” Patrick said in an interview with CBS This Morning.

He praised the “really talented and really gifted” field of Democrats already seeking the nomination but said he saw an opportunity for someone with his vision.

In what appeared to be a swipe at the party frontrunners, the former vice-president Joe Biden and the Massachusetts senator Elizabeth Warren, Patrick said: “We seem to be migrating on the one camp toward nostalgia … and on the other camp it’s ‘our big idea or no way’.”

Asked where he stands on key Democratic issues, Patrick said he does not support Medicare for All “in the terms we’ve been talking about” but plans to push for a “public option”. He said he supported raising taxes “on the most prosperous and the most fortunate, not as a penalty but because we all have a stake as a national community in building our future”.

Patrick was expected to appear in New Hampshire, where he will enter February’s primary. He is also expected to focus hard on South Carolina, an early voting state with a sizeable African American electorate.

In his YouTube video, Patrick discussed his youth in the South Side of Chicago and his experience in “government, nonprofits and in business”. Among items on Patrick’s CV not mentioned in the video was a post-statehouse spell working for Bain Capital, the private investment firm founded by Mitt Romney, the 2012 Republican nominee.

The 63-year-old was governor of Massachusetts from 2007 to 2015, the first African American in the post, and is a close ally of the former president Barack Obama.

His entry into the 2020 race follows the former New York mayor Michael Bloomberg filing to enter state primaries, though he has made no final decision about whether he will run.

Bloomberg’s flirtation with a run has been attributed to Biden’s missteps and faltering polling numbers. The former vice-president is seen as the centrist choice in a sprawling field against Warren and Bernie Sanders, a senator from Vermont.

Pete Buttigieg, the 37-year-old mayor of South Bend, Indiana, rounds out the top four in polling, surging strongly in Iowa, the first state to vote. No one else has made a significant mark.

Defeating Trump is seen as paramount among a Democratic establishment worried the primary is shifting too far left.

“I admire and respect the candidates in the Democratic field,” Patrick said in the YouTube video. “They bring a richness of ideas and experience and a depth of character that makes me proud to be a Democrat. But if the character of the candidates is an issue in every election, this time it’s about the character of the country.”

He did not mention Trump by name. The 2020 election, he said, will be about “the character of the country … about more than removing an unpopular and divisive leader, as important as that is.”

He then promised to build a more inclusive America, declared his candidacy and vowed to “build as we climb”.

In an interview with the Boston Globe, Patrick acknowledged that his presidential campaign was a long shot, comparing it to a desperate football pass thrown as a last resort.

“This is a Hail Mary from two stadiums over,” he said.