Trump has long attacked career diplomats as members of the “deep state,” and his volleys have only intensified since the House of Representatives’ public impeachment hearings began last week. The president’s criticism of Marie Yovanovitch, the former U.S. ambassador to Ukraine, has galvanized support among her current and former Foreign Service colleagues: Many high-profile and lesser-known diplomats have been tweeting with the hashtag #FSProud.

Read: Why Trump attacked Marie Yovanovitch

I spoke with former ambassadors and civil-service and Foreign Service officers, nearly all on condition of anonymity to discuss their positions. They have been writing policy speeches and position papers, advising (sometimes multiple) Democratic candidates, and in some cases actively campaigning and fundraising for the first time. Most of the nearly two dozen former diplomats I spoke with have not previously backed a primary candidate from either party; the extent of their political participation stopped at voting. Now they say they intend to support whichever Democrat makes it to the general election, assuming Trump is the Republican nominee. Most said they’d want to return to duty under a new administration, despite settling into retirement or private-sector jobs at think tanks or in academia. (While it’s not uncommon for former political appointees throughout the government to go on to participate in electoral campaigns, career civil-service and Foreign Service officers typically spend decades moving up the ranks in government and therefore traditionally serve under both Republican and Democratic administrations.)

The union that represents diplomats said in November 2017 that the State Department had lost 60 percent of its career ambassadors. They were either fired, pushed to resign, or reassigned, according to personal statements released upon departure, interviews after the fact, and media reports. In May 2018, Secretary of State Mike Pompeo rescinded a 16-month-long hiring freeze implemented by his predecessor, and the numbers have slowly started to climb back up. But Pompeo has also attempted to fill career vacancies with political appointees, sparking a showdown with Senate Democrats.

Read: The hollowing-out of the State Department continues

Of those diplomats who have departed, some have joined Biden’s campaign, having worked with him directly in the past. Buttigieg has also attracted interest from Obama-Biden folks who who miss having an idealistic and savvy young political hotshot at the top of the ticket. Others who felt the Obama administration was too slow to respond to humanitarian crises have begun advising Warren and, to a lesser extent, Bernie Sanders.

“I co-hosted my first fundraiser a few weeks ago, and part of it is the sense of duty, but also as a Latino and somebody who feels the Latino community is completely under attack, I feel like I need to invest everything I can to help get Donald Trump out of office,” a former diplomat who is advising the vice president told me recently. “I feel like Joe Biden, with his experience in Latin America and actually knowing how to negotiate with both sides of the aisle to get stuff done, is the best way to do it. And I would at the drop of a hat serve under him if he were to be elected.”