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 GillibrandTwo years after Maria, Puerto Rico awaits disaster funds Defense bill talks set to start amid wall fight Democrats seize Senate floor to protest gun inaction: 'Put up or shut up' MORE (D-N.Y.) and Elizabeth WarrenElizabeth Ann WarrenOvernight Health Care — Presented by Partnership for America's Health Care Future — Pelosi unveils signature plan to lower drug prices | Trump says it's 'great to see' plan | Progressives pushing for changes Buttigieg calls Warren 'evasive' on Medicare for all Sanders hits 1 million donors MORE (D-Mass.), former Vice President Joe BidenJoe BidenGiuliani clashes with CNN's Cuomo, calls him a 'sellout' and the 'enemy' Giuliani says 'of course' he asked Ukraine to look into Biden seconds after denying it Trump whistleblower complaint involves Ukraine: report 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