(CNN) Massachusetts Rep. Seth Moulton is the latest Democrat to enter the 2020 presidential race, launching a longshot bid Monday that would make the 40-year-old Marine Corps veteran the youngest president in American history.

"I am here to tell you and to tell America that I am running for President of the United States," Moulton said in an interview Monday on ABC's " Good Morning America

"And I am running because I am a patriot, because I believe in this country and because I have never wanted to sit on the sidelines when it comes to serving it," Moulton said. "That is why I joined that Marines, it is why I ran for Congress to try to prevent what I saw got us into Iraq from happening again, and it is why I am running to take on the most divisive president in American history to bring this country back together."

Moulton joins a large -- and growing -- field of Democratic candidates in 2020. The Massachusetts Democrat is the 19th candidate to announce a presidential campaign and the field is expected to grow this week when Vice President Joe Biden makes his long-anticipated presidential announcement.

In a campaign video posted earlier Monday morning, the Democrat touted his military service and time in Congress and explained why he believes he should be the party's next presidential nominee.

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