Story highlights Liberals like Bernie Sanders, Elizabeth Warren and Al Franken are grilling Trump cabinet nominees

They are using the hearings to position themselves as Democratic Party leaders

Washington (CNN) Hearings for Donald Trump's Cabinet nominees are serving as auditions for Democrats who want to be the party's next liberal leader. Or in the mix to be the 2020 presidential nominee.

As President Barack Obama leaves office and Hillary Clinton fades from the political scene, experience as a national party leader is what Democrats now lack -- and confirmation hearings for Trump's picks have served as a test run for the party's top voices.

Trump picks like Betsy DeVos (education), Steven Mnuchin (treasury), Scott Pruitt (EPA), Tom Price (HHS) and Jeff Sessions (attorney general), have been facing a line of liberals waiting to make their name on the national stage.

Elizabeth Warren and Bernie Sanders -- two national leaders familiar to liberals -- have used the hearings to portray Trump's nominees as unqualified and determined to undercut the core tasks of the agencies they've been chosen to lead. Minnesota's Al Franken, Washington's Patty Murray and New Hampshire's Maggie Hassan have attracted Democrats' attention with key moments of their own.

And New Jersey's Cory Booker became the first senator to ever testify against another senator when he opposed Alabama Sen. Sessions' nomination for attorney general in front of the Senate Judiciary Committee.

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