Billionaire and liberal philanthropist George Soros has been telling his aides that he may not back a candidate during the 2020 Democratic presidential primary as the potentially large field sorts itself out.

"He doesn't plan to pick a horse in this race," Michael Vachon, Soros' chief spokesman, told CNBC in an email after being asked where his boss stands on the growing list of possible Democratic candidates for president.

Vachon explained that the Democrats who will be in the running for the nomination will likely not see a commitment from Soros because "he thinks there are several good candidates." Vachon did not name the candidates Soros praised.

Holding off on backing a candidate during the primary would mark a change in tactics for Soros. In the buildup to the 2016 general election, Soros supported Hillary Clinton over liberal Sen. Bernie Sanders of Vermont. His backing included a $343,000 contribution to the Hillary Victory Fund, a joint fundraising committee supporting Clinton and the Democratic National Committee, according to Federal Election Commission filings.