A few months ago, the contenders for the Democratic Party nomination were getting along swimmingly.

It was nice while it lasted.

I have always admired Hillary Clinton’s ambition. What’s distressing is how far she’s willing to go to fulfill it. As we learned in 2008, Clinton plays nice when an unlikely rival first appears out of nowhere, steadily gaining in popularity and momentum. But as soon as it’s clear that her challenger poses a real threat , she panics and whips off the gloves.

In 2008 she assured “60 Minutes” that then-Sen. Barack Obama was not a Muslim, “ as far as I know .” Many interpreted the qualifying phrase as insinuating that Obama could be a Muslim. Others insisted that members of the media were reading too much into that final clause.

That remark was open to interpretation; other tactics were unambiguously dirty. It was reported in 2008 that Clinton staffers circulated a photo of Obama in African dress to fuel rumors that he was a Muslim. Her campaign’s New Hampshire co-chairman, Bill Shaheen, resigned in 2008 after raising questions about Obama’s teenage drug use, and two Iowa volunteer coordinators resigned after forwarding emails about Obama’s nonexistent Muslim identity. Mark Penn, Clinton’s chief campaign strategist early in her 2008 run, advised the campaign in a 2007 memo to emphasize Obama’s “lack of American roots.” Penn, too, ultimately resigned.

By contrast, the most notable resignation from the Obama campaign was that of Samantha Power, now the U.S. ambassador to the United Nations, who resigned after calling Clinton a “monster” who would stoop to anything to get elected.

It is possible neither Clinton nor her senior advisers, aside from Penn, knew of or condoned these dirty tactics. But she certainly has a high tolerance for slimy operatives who specialize in sewing doubt and fear. During this year’s campaign, she has accused her top rival, Bernie Sanders, of wanting to “ tear up” the Affordable Care Act and dispatched her daughter to frighten voters with the specter of a Sanders health care plan that would strip low-income people of Medicaid . Both claims are patently false. He favors a single-payer health care system that would extend coverage to all Americans, not take it away. Clinton knows this, and it is disingenuous to say otherwise.