Washington (CNN) Democratic presidential candidate Sen. Amy Klobuchar on Sunday joined others vying for the party's nomination in taking issue with Michael Bloomberg's potential 2020 bid and criticizing the former New York City mayor's billionaire status.

"And when people look at the White House and they see this multi-millionaire (President Donald Trump), including, by the way, independents, moderate Republicans, and how now he's messing up so many things, I don't think they say, 'Oh, we need someone richer.' I don't think that, Jake. I think you have to earn votes and not buy them," Klobuchar told CNN's Jake Tapper on "State of the Union," adding to the lukewarm reception given in recent days to the billionaire politician by members of the crowded field of candidates.

The move is the clearest sign to date that the former three-term mayor is seriously considering following through with something he has been weighing for weeks. Bloomberg, whose media empire helped him amass a net worth of $51 billion, is the 8th richest person in America, according to Forbes. (Trump is 275th on that list, with an estimated net worth of $3.1 billion.)

Klobuchar said Sunday that she welcomes the former mayor into the contest, noting that he has done "incredible work" on gun safety and environmental issues. But the Minnesota Democrat also told Tapper that she doesn't think Bloomberg can "just waltz in" and say, "I'm good enough to be president" and that "the other people aren't good enough."