Former congressman Joe Sestak, D-Pa., ended his presidential campaign on Sunday, a little over five months after he launched his long-shot bid for the Democratic nomination.

The move brings the number of Democratic contenders to 17, with the Iowa caucuses roughly two months away.

On Twitter and in an email to supporters, Sestak voiced his gratitude for "this priceless opportunity as I end our campaign together."

"Without the privilege of national press, it is unfair to ask others to husband their resolve and to sacrifice resources any longer," he wrote. "I deeply appreciate the support so many of you offered - whether by volunteering, offering financial contributions or coming to our campaign events. I will miss the opportunities I had in experiencing America in such a wonderful way!"

Sestak, a retired Navy admiral, announced his presidential bid in June with a video that highlighted his military service and his anti-establishment credentials.

The former two-term congressman pursued two unsuccessful Senate bids, in 2010 and 2016. Each time, his go-it-alone style earned him the ire of many national and state Democrats.

During his 2010 bid, he drew national attention by defeating then-Sen. Arlen Specter in the Democratic primary; Specter had switched parties to run for reelection as a Democrat. Six years later, Sestak walked alone across the state of Pennsylvania for about a month, averaging about 20 miles a day.

Sestak gained little traction in the 2020 race, however, and did not make it to the stage for any of the Democratic debates.

"A moral compass for our great ship of state is the beacon most needed today," Sestak, who has shown a fondness for using naval metaphors in his campaigns, wrote in his departure letter. "And it is for the Captain of State who offers it that all Americans will provide the fair winds and following seas to advance us. That is necessary for us both at home and abroad, to convene the world to advance our policies and commitment to democratic values for our collective good."