David E. Vogt III of Brunswick briefly sought the GOP nomination for the seat in the 2014 cycle before deciding instead to run a successful campaign for a seat in the House of Delegates.
"Today, I am announcing my campaign for Congress because I believe it is time for a fresh voice to represent Maryland's 6th Congressional District," Vogt, who is 30, wrote to supporters in an email on Tuesday.
The 6th District will be an uphill fight for a Republican, despite GOP nominee Dan Bongino's better than expected showing last year. That's in part because turnout in Democrat-heavy Montgomery County is likely to be higher during a presidential year.
There's little risk for Vogt in tossing his name in for the race: He can retain his seat in the legislature even if he loses for Congress.
Vogt served in the Marines for eight years on active duty, from 2004 until 2012, including a tour in Afghanistan.