Dan Baer, a former ambassador and U.S. Rep. Ed Perlmutter’s only remaining Democratic challenger, said Wednesday he’s dropping his bid to represent Colorado’s 7th Congressional District.

Three other Democrats – state Sens. Andy Kerr and Dominick Moreno and state Rep. Brittany Pettersen – ended their campaigns for the suburban seat in late August within days of Perlmutter’s announcement that he planned to run for a seventh term in Congress. Perlmutter had earlier said he wouldn’t seek re-election – first in April, when he launched a campaign for governor, and again in July when he withdrew from that race.

“I wanted to make an argument about the future and not about a popular Democratic incumbent,” Baer told Colorado Politics.

“It’s going to be very important to me to see that President Trump is not re-elected in 2020,” he added. “I will be part of a group of folks working to restore dignified, principled American leadership both at home and abroad.”

Baer, 40, served as U.S. ambassador for the Organization for Security and Co-operation in Europe in the Obama administration and was recently named a diplomat in residence at the University of Denver’s Josef Korbel School of International Studies.

Republicans have yet to field a candidate for the seat, which includes portions of Jefferson and Adams counties.

After raising $300,000 in the first two weeks of his campaign, Baer said he believed he could “muster the resources” to mount a serious bid for the seat but wrestled with the differences between challenging a longtime incumbent and running for what had been – if only briefly – an open seat. “Is this a campaign I can run and still be me?” he said. “In the end, I decided in 2018 the stakes were too high.”

“I felt fortunate that I had raised enough money by the time Ed was reentering the race so I could afford to press pause. I decided I didn’t want to make a decision without thinking through what the new context of the campaign meant for my campaign. I took the time to do that,” he said.

“As someone who has grown up in Colorado, Dan brings a wealth of experience and talent back to the state,” Gov. John Hickenlooper said in a statement. “We admire his commitment to public service and hope his desire for contributing remains strong. He will no doubt bring impact no matter what the future holds.”

Baer said he would determine what to do with campaign funds – he said he didn’t have a final accounting but noted he’ll be filing a report with the Federal Election Commission by Oct. 15 – in coming weeks.

Rachel Irwin, regional press secretary for the Democratic Congressional Campaign Committee, said Baer’s qualities as a candidate highlighted the depth of the party’s bench in the state.

“We’re impressed by the many Democratic candidates who stepped forward to run for this seat,” she told Colorado Politics. “Former ambassador Daniel Baer has a bright future within the Democratic Party and will be a strong voice fighting for progressive values in Colorado. He adds to a growing bench of young stars who will serve our party well into the future.”

Baer told Colorado Politics it had been a difficult decision to step back from the race after spending months in all-out congressional campaign mode.

“This isn’t the way I expected things to turn out when I jumped in,” he said. “This has been a shorter ride than I expected. And I’m disappointed. But I’m really encouraged that when I’ve been out there talking with voters, there is a deep hunger to turn the page and have an optimistic view of the future. That’s what I found fulfilling and energizing.”

As the community was facing the aftermath of the mass shooting in Las Vegas and the devastation wrought by Hurricane Maria in Puerto Rico, Baer noted,  “This has been an enormously dark week for our country. This is not an easy time to feel hopeful, and I have been encouraged by the people of the 7th District and their determination to find rays of hope.”