Former Wisconsin Gov. Scott Walker (R) called Democratic presidential candidates Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE and Elizabeth Warren Elizabeth WarrenOvernight Defense: Appeals court revives House lawsuit against military funding for border wall | Dems push for limits on transferring military gear to police | Lawmakers ask for IG probe into Pentagon's use of COVID-19 funds On The Money: Half of states deplete funds for Trump's 0 unemployment expansion | EU appealing ruling in Apple tax case | House Democrats include more aid for airlines in coronavirus package Warren, Khanna request IG investigation into Pentagon's use of coronavirus funds MORE "wannabe socialists" in an interview that aired Sunday.

Speaking with radio host John Catsimatidis on AM 970's "The Answer," Walker implied that Democratic candidates including Biden, Warren and Sen. Bernie Sanders Bernie SandersSirota reacts to report of harassment, doxing by Harris supporters Republicans not immune to the malady that hobbled Democrats The Hill's Morning Report - Sponsored by Facebook - Republicans lawmakers rebuke Trump on election MORE (I-Vt.) would mess up the economy if they're won the presidency.

"Middle class working America were big winners under this presidency and it's why the last thing you want to do is screw it up and put a socialist like Bernie Sanders or other...wannabe socialists like Elizabeth Warren or Joe Biden in," Walker said.

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Biden, Warren and Sanders are considered the frontrunners in a crowded 2020 Democratic presidential field. Sanders has described himself as a democratic socialist but the others have not done so.

Warren said in March that it would be "wrong" to call her a socialist.

Walker ran unsuccessfully for the Republican presidential nomination in 2016 and his gubernatorial reelection bid last year.