If Biden continues to fade, Patrick will try to fill the vacuum. A pro-Patrick super PAC, Reason to Believe, has pumped hundreds of thousands of dollars into South Carolina media markets in recent weeks, with an emphasis on black radio. Patrick's wife has made two solo trips to campaign in the state in recent weeks while Patrick spends time in New Hampshire.

Reason to Believe has reserved well over $600,000 in airtime in South Carolina — $253,000 in Charleston, $246,000 in Columbia and $186,000 in Greenville, and more cash is on the way, according to a supporter of the super PAC who declined to be named — but predicted that Patrick would finish first or second in the state, which votes Feb. 29.

It's a bold statement to make on behalf of a presidential candidate who is hardly registering in the polls. But Patrick is the only black candidate left in the 2020 primary and only the second elected black governor in American history. That could help his standing among the majority of South Carolina's Democratic voters who are black.

But Patrick is not the only candidate who sees opportunity in the first Southern primary. Tom Steyer, a billionaire businessman, has been spending millions on television and digital ads there. Steyer's campaign announced on Thursday that he will travel to South Carolina on Sunday to host a block party, and will hold a town hall in the state on Monday.

The decision to leave New Hampshire in the critical two days leading up to the primary, when the other candidates will put an emphasis on retail politics, is a sign Steyer sees opportunity elsewhere, potentially from the same potential shakiness in Biden’s campaign that Patrick is eyeing. Polling still puts Biden in first place in South Carolina, followed by Sanders and Steyer.

But while Steyer has millions of his own dollars to spend spreading his name, name recognition is one of Patrick’s biggest challenges: After his second term as governor, he left public life to work at Bain Capital.

The Reason to Believe ad buy comes as at least one other candidate frees up some space on the airwaves. Massachusetts Sen. Elizabeth Warren canceled a $350,000 flight in Nevada and South Carolina from Feb. 17 to Feb. 23. Warren told reporters she's being "careful" with her money during a campaign stop in Nashua on Wednesday.

Patrick's campaign has put its own ads on the air in South Carolina, too. Having entered the race close to a year after his Democratic rivals, Patrick has been focusing on the primary states, rather than the early caucus states, Iowa and Nevada, that require more organization and infrastructure.

Patrick has 20 staffers in South Carolina and an office in Columbia. The former governor has made nine trips to the state since he entered the presidential race in November and has met with influential Rep. Jim Clyburn.

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"I've been in South Carolina more than any other candidate," Patrick said in an interview during a bus tour across New Hampshire last week. "I've been all over the state."

Patrick has also ratcheted up his criticism of the Democratic frontrunners in recent days. Patrick slammed top-tier candidates Biden and Buttigieg, saying both men reacted to the Iowa caucus results in the style of President Donald Trump.

"One candidate is calling the results into question because he apparently didn’t do well. Another is declaring victory without any votes being confirmed," Patrick said on Tuesday. "The way to beat Donald Trump isn’t to act like Donald Trump. Our party and our country deserve better.”

The following day, Patrick knocked Biden again, tweeting that he sounded scripted and calculated in an attack on Buttigieg. The former vice president had referenced Buttigieg by name in a tweet.

"This back-and-forth sounds like it was scripted by pollsters from past elections. If we want to win, and deliver, we need to be bigger and better than this," Patrick wrote online.