WASHINGTON _ Bob Buckhorn remembers sitting at home in Florida last month watching the first Democratic presidential debate _ and openly worrying about what he was seeing.
The former centrist Democratic mayor of Tampa said the candidates were lurching much too far to the left on key policy issues, damaging the party's chances of defeating President Donald Trump during next year's election.
"I don't think most Americans are comfortable with some of what they heard last debate," Buckhorn said. "And I think it's unfortunate."
Buckhorn's view is a common one among moderate Democrats. In interviews, many of them expressed deep concern that this week's debate in Detroit will feature another inevitable shift to the left, one that will alienate swing voters in battleground states like Pennsylvania, Michigan, and Wisconsin.
Last month, Democratic candidates debated _ and in many cases, embraced _ issues like eliminating private health insurance and decriminalizing illegal border crossings that are unpopular with the broader electorate.
Even some of those who will participate in the debate are unsure where the conversation will move next.
"This primary is becoming about moving the goalposts on these issues," said John Delaney, one of the presidential race's most outspoken moderate candidates. "And you never know what the next one is going to be."
Primaries traditionally encourage candidates to back policy proposals that appeal more to the party's ideologically fervent base than moderates In most cases, whoever emerges as the eventual nominee inevitably pivots back toward the center for the general election.
But centrist Democrats say the last debate was, even for a primary, unusually fixated on subjects that either didn't interest or outright repelled voters in the middle of the political spectrum.
"I hope that in the next debate there's more of a discussion about education and public safety and issues of the economy and those other issues that a lot of moderates are looking for," said former Democratic Sen. Mark Begich of Alaska.
Even more alarming, they said, was the speed at which some once-fringe issues were widely adopted by the presidential field, like decriminalizing border crossings.
The idea gained broad acceptance among most of the candidates after being introduced by former Housing and Urban Development Secretary Julian Castro _ despite polls showing that it had little support among the broader public and even uneven backing within the Democratic Party.
Just 27% of Americans say it would be a good idea to decriminalize border crossings while 66% say it would be a bad idea, according to a NPR/PBS NewsHour/Maris poll released last week. The idea has split support among Democrats, with 45% saying it would be a good idea and 47% saying it's a bad idea.
Moderate Democrats say they want White House hopefuls to condemn Trump's immigration policies and show support for plans that grant citizenship to undocumented immigrants. But discussion that avoids any talk of border security is politically dangerous, they argue, especially with a president who plans to make immigration the centerpiece of his reelection campaign.
"What President Trump would like to do is for us to talk about the rights of Central Americans instead of the rights of American citizens," said Scott Peters, a moderate Democratic congressman from the San Diego area. "And we can't fall into that trap."
Peters, a member of a center-left group in the House called New Democrats, encouraged his party's presidential candidates to emulate the agenda and style of the host of freshman Democrats who won battleground districts during last year's midterm elections.
Most of them focused their general-election campaigns relentlessly on GOP efforts to repeal the Affordable Care Act, which would remove protections for men and women with pre-existing medical conditions, while touting a liberal if more pragmatic set of policy proposals.
That's aligned with the approach of some presidential candidates, most notably former Vice President Joe Biden, who has argued that he wants to preserve Obamacare while criticizing some of his opponents for wanting to switch instead to a single-payer system.
"We should all be concerned that we not lose touch with those people who are going to really matter in winning this election," Peters said. "I was surprised that there wasn't more of a defense, for instance, of Obamacare, and a defense of an immigration policy that helps our economy and recognizes the importance of borders at the same time."
The conflict between liberal and moderate Democrats in part stems from different views of how the party can defeat Trump. For some progressives, they think the key is driving up turnout among their core base.
For more politically centrist Democrats like Jeff Smith, a former state lawmaker in Missouri, the key is winning over more moderate independent voters.
Smith said when he watched last month's debate in a right-leaning part of his home state, he kept thinking how few people near him would agree with what the Democratic presidential candidates were saying.
Missouri isn't a swing state, he said, but many of the middle-of-the road voters in the state are similar to the ones Democrats need to win over in Wisconsin and Michigan next year. It's why he wishes the candidates would steer the conversation to policies with more support, he said, despite his own ideological convictions.
"Am I for most of those things? Yes, I'm for most of those things," Smith said. "I also know that in the span of 18 months, we aren't going to change enough minds to make those the median voters' position."
