It happened only last week, but Congressman Seth Moulton’s official entry into the race for the 2020 Democratic presidential nomination already feels months old.

Perhaps that is because the three-termer had been teasing the move for weeks, if not months, making visits to the early season hot spots of Iowa and South Carolina and popping up regularly on TV to chat with the talking heads of cable news, all the while coyly dodging questions about his national ambitions.

By the time Moulton made his announcement last Monday — in a subdued, early morning one-on-one with George Stephanopoulos of Good Morning America and not with a rally in his home district — the 40-year-old Harvard graduate and Marine veteran was only one of more than 20 Democrats hoping to unseat Republican Donald Trump. And any attention Moulton may have attracted last week was quickly subsumed by the cacophony surrounding former Vice President Joe Biden’s entrance into the race.

Moulton says he wants to draw attention to areas other presidential candidates aren’t talking about, specifically veterans’ issues, national security, defense and foreign policy. And like the other prospective nominees, he will talk about the incumbent.

“I will always uphold America’s values,” he said in the video announcing his campaign. “I’m running because we have to beat Donald Trump, and I want us to beat Donald Trump because I love this country.”

A presidential field filled with strong, diverse candidates is a good thing for the country. So, too, is the notion of a strongly contested race on the local level.

The Marblehead native’s national candidacy has led to much local speculation about what will happen with “Moulton’s seat” in Congress. Moulton says he plans to run for a fourth term in the 6th District should he fail in his long-shot bid for the presidency.

The congressman would be wise to remember the lessons of “Kennedy’s seat.” In 2010 Massachusetts Democrats expected to win in a walkover the special election to fill the vacancy left by the death of U.S. Sen. Ted Kennedy. That overconfidence led to an disengaged campaign by Attorney General Martha Coakley and the election of Republican Scott Brown, then a state senator whom many treated as an afterthought.

Moulton should know more than most that no seat is safe in this new political era, having famously ousted longtime incumbent John Tierney in the Democratic primary of 2014.

While Moulton has been re-elected easily since then, he was uncontested in one race and faced a Republican with no name recognition and few local ties in the other. Meanwhile, many North Shore Democrats haven’t forgiven him for taking on Tierney in the first place. He further angered many in his party by trying to oust Nancy Pelosi as the leader of the party in the House of Representatives. The effort garnered him national attention but did little to endear him with many in his home district. He was met with a loud round of boos when he tried to defend his position at an Amesbury town hall meeting last year.

So as Moulton continues his tour of presidential primary states, a slate of potential challengers is taking shape back home. There’s Lori Ehrlich, the veteran state representative from Moulton’s hometown who has added to her progressive record on Beacon Hill in recent years. There’s Jamie Zahlaway Belsito of Topsfield, a Salem State University trustee and founder of Effie’s Grace, which advocates on women’s health issues. Governor’s Councilor Eileen Duff of Gloucester may get into the race. And former state Sen. Barbara L’Italien of Andover, fresh off an unsuccessful bid for the 3rd Congressional District seat, is mulling a new run in a new neighborhood.

Looming over them all is Tierney, who is being urged to run by old Democratic Party friends across the region.

Now executive director of the national security and foreign policy think tank Council for a Livable World, the former nine-term congressman said he is “keeping an open mind” on a fresh run. He still has enough old friends in the party — including Pelosi — and in the region to quickly field a campaign team.

Last week, spokesman Matt Corridoni told reporter Ethan Forman that Moulton “has said before he was elected via a primary and he’s not afraid of democracy.”

That is a good thing, for the congressman and for the district, because it appears democracy will be in abundant supply over the next several months, both nationally and back at home.