South Carolina mayor says conventional wisdom will be tested in 2020 Dem primaries

Conventional wisdom will be put to the test in the 2020 Democratic primaries, according to Columbia, S.C., Mayor Stephen Benjamin (D).

"I think all bets are off the table in [that] no one who's smart will take anything for granted," Benjamin told Hill.TV's Jamal Simmons on "Rising."

"They'll come and spend the time learning the state, talking to them about what's important," he added in a Tuesday interview that aired the following day.

"I think some of the conventional wisdom will be tested this time," he said, referring to the primary season as a whole.

South Carolina's will be the third primary contest in 2020, after the Iowa caucuses and the New Hampshire primary.

"Everyone is going to have to come and grind it out," he said. "Julián Castro was a fantastic HUD [Housing and Urban Development] secretary. He was very good, I will tell you, to the people of Columbia during his tenure in the Obama administration." 

Castro launched his White House bid earlier this month.

Benjamin also praised other candidates and potential contenders, including Sens. Kirsten GillibrandKirsten Elizabeth GillibrandDemocratic strategist predicts most 2020 candidates will drop out in late fall The Hill's 12:30 Report: Trump hits media over 'send her back' coverage The Hill's Campaign Report: Second debate lineups set up high-profile clash MORE (D-N.Y.) and Elizabeth WarrenElizabeth Ann WarrenJulián Castro is behind in the polls, but he's finding a niche Gabbard arrives in Puerto Rico to 'show support' amid street protests Democratic strategist predicts most 2020 candidates will drop out in late fall MORE (D-Mass.), former Vice President Joe BidenJoe BidenBiden compares Trump to George Wallace Sanders unveils plan to guarantee the 'right to a secure retirement' CNN Democratic debate drawing finishes third in cable news ratings race MORE and former New York City Mayor Michael Bloomberg.

The field of presidential hopefuls is expected to grow in the coming weeks. 

A Harvard CAPS/Harris Poll survey released exclusively to The Hill on Tuesday found that 43 percent of respondents said they would cast their vote for a Democratic candidate in 2020.

— Julia Manchester