(CNN) Sen. Elizabeth Warren on Friday pledged not to give ambassador posts to donors if she becomes president and said she would fill certain senior-most positions at the State Department with career ambassadors.

The promises were part of the new plan the Democratic presidential candidate unveiled aimed at the State Department. The Massachusetts Democrat wrote in Medium Post that President Donald Trump has "declared war" on the department and that it will take "a whole lot of work" to get enough qualified diplomats back into the government. She also slammed Trump for "selling swanky diplomatic posts to rich buffoons," although Trump is not the first president to appoint financial backers of his campaign to ambassador posts.

"This president may think a fat wallet and a big campaign check qualifies someone to represent our country abroad," she wrote. "I'm pledging to put America's national interests ahead of campaign donations and end the corrupt practice of selling cushy diplomatic posts to wealthy donors -- and I call on everyone running for President to do the same. I won't give ambassadorial posts to wealthy donors or bundlers -- period."

As a part of her plan, Warren proposed doubling the size of the foreign service and opening new diplomatic posts in places in the world that she sees as "underserved areas."

To achieve the goal of encouraging younger people to join the foreign service, the presidential candidate said she would create a "diplomatic equivalent of the ROTC program" to promote recruitment, and also pledged to double the size of the Peace Corps.

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