(CNN) Sen. Elizabeth Warren on Tuesday challenged her Democratic primary rivals to release the names of contributors and fundraisers with influential positions on their campaigns, while pledging to champion legislation that would effectively disqualify big-dollar donors from being appointed to cushy diplomatic posts.

The requests were written into a series of mostly new proposed campaign finance restrictions, which would ban corporate PACs from donating to federal candidates and make it illegal for certain super PACs to be run by operatives with professional or personal ties to the candidate they're backing.

Now firmly among the front-runners for the Democratic presidential nomination, Warren has increasingly centered her campaign on a broad anti-corruption platform . In past rollouts, she promised to forbid lobbyists from making political contributions, acting as bundlers or hosting fundraisers for candidates. Former top federal officials -- including presidents, vice presidents, members of Congress, judges, and cabinet secretaries -- would also be permanently prohibited from taking lobbying jobs.

While Warren does not name any of her competitors in her Medium post, the new call for campaigns to "disclose any donor or fundraiser who has a special title on their campaign, including national and regional finance committee members and bundler designations" is an apparent nudge to a number of top rivals, like former Vice President Joe Biden, South Bend, Indiana, Mayor Pete Buttigieg and California Sen. Kamala Harris, who all regularly attend big-dollar fundraising events.

Warren's call to cut off the donor-to-ambassador pipeline, which she acknowledges has been common practice in both Republican and Democratic administrations, comes with increased resonance now that President Donald Trump's EU ambassador, Gordon Sondland , a Republican megadonor who gave $1 million to Trump's inaugural committee, has emerged as a key figure in the Ukraine scandal.

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