Since he entered the House in 1999, Joseph Crowley has always stayed in his party’s ideological mainstream. But that mainstream was once much more conservative than it is today. Crowley’s a Catholic. And like many Catholic Democrats in the 1990s and 2000s, he sought a middle ground on abortion. While supporting abortion rights, he in 2000 and 2003 backed legislation to ban the procedure dubbed “partial-birth” abortion. He sought a middle ground on the economy too. Crowley was no Ted Cruz: He opposed George W. Bush’s 2001 tax cuts. But like many Clinton-era Democrats, he sought to prove that Democrats were not anti-business or anti-Wall Street. In 1999, he voted to overturn the 1933 Glass Steagall Act, which restricted the activities of banks. In 2002, he earned a lukewarm 78 percent rating from the AFL-CIO. In the wake of 9/11, when many Democrats feared being caught on the wrong side of the nation’s surging jingoism, Crowley embraced hawkish stands that slighted civil liberties. He backed a constitutional amendment banning flag burning. He supported the Patriot Act. He voted for the Iraq War.

At the time, none of this made Crowley an ideological outlier. Many nationally ambitious Democrats—from Bill Clinton to Hillary Clinton to Al Gore to John Kerry to Richard Gephardt—took similar stances. Their centrism stemmed partly from ideological conviction. (Many Democrats worried that excessive regulation had contributed to the economic stagnation of the Carter years. Many had grown more hawkish as the result of America’s military victories in the Gulf War and the Balkans in the 1990s). And their centrism stemmed partly from fear of right-wing attacks and the need to raise money from big business and Wall Street. Like many of his party’s leaders, Crowley was a “New Democrat.” Indeed, for four years he chaired the New Democrat Coalition in Congress.

But in recent years, the New Democratic wing of the Democratic Party has withered. And in response, Crowley has shifted left to stay in his party’s mainstream. After initially supporting legislation to weaken the Dodd-Frank restrictions on Wall Street, in 2015 he came out against it. After initially praising the Trans-Pacific Partnership (TPP), he turned against it too.

Other Democrats have followed a similar path. John Kerry, who also voted to authorize the Iraq War, voted against funding it while facing a fierce anti-war challenge in the 2004 Democratic primaries from Howard Dean. After losing to Barack Obama in 2008 in part because of her vote for the Iraq War, Hillary Clinton apologized for it in the run-up to her 2016 presidential bid. She also reversed her prior support for TPP and dramatically distanced herself from her husband’s punitive anti-crime policies.

The problem for Crowley, like Kerry and Clinton, was that their newfound progressivism didn’t appear genuine. Although they now checked the boxes as stalwart progressives, their prior careers as New Democrats made them suspect to a party base hungry for authenticity and courage. Which helps explain why Kerry almost lost to Dean in 2004, why Obama beat Clinton in 2008, and why Clinton faced such a formidable challenge from Bernie Sanders in 2016.