Max Rose, a moderate Democrat who lost his congressional seat last year amid a resurgence of Republican power in parts of New York, announced on Monday that he was mounting another run for Congress, setting up a national political battleground in New York City.

The race for New York’s 11th Congressional District, currently held by Representative Nicole Malliotakis, a Republican, could be one of the most competitive in the metropolitan area next year, along with possible races on Long Island.

Depending on the contours of the Staten Island- and Brooklyn-area district following the redistricting process, the contest may also represent one of the Democrats’ more promising pickup opportunities, as they strain to maintain their congressional majorities heading into a grueling midterm campaign environment.

The race may also offer a revealing snapshot of how Democrats in key battlegrounds choose to position themselves, after the Republican Party gained ground over the last year by portraying Democratic candidates as anti-law enforcement.

Mr. Rose announced his intentions in a brief video in which he discussed what he cast as the promise of American exceptionalism, even as he nodded to the challenges facing the country, including inflation, natural disasters, the coronavirus pandemic and the extraordinarily violent political climate laid bare by the Jan. 6 insurrection.

“The alarm bells, they never stop ringing, and the people we trust to fix it, they divide us, they lie to us, tearing America apart, just to hold on to power,” Mr. Rose said in the video, as images of the United States Capitol under siege flashed across the screen. “You look at all that and it’s easy to think that maybe our best days are behind us, that nothing will change. Well, I disagree.”

Ms. Malliotakis voted against certifying the results of the 2020 election even though former President Donald J. Trump’s claims of a stolen election are false — a vote that will almost certainly become an issue in the congressional race.

Last year, she beat Mr. Rose by around six percentage points, though Mr. Rose outperformed President Biden’s showing in the district, which includes strongly pro-Trump Staten Island. In that race, she sought to use Mr. Rose’s decision to join a march for racial justice as a cudgel, and he appeared to allude, in part, to that moment in his video as he discussed doing what he “thought was right” in the face of political consequences.

It is not yet clear how redistricting will change the political dynamics of the district, but given Mr. Rose’s experience with challenging national headwinds, his decisions regarding campaign strategy and messaging will be closely watched as he competes in the Democratic primary.

“It should not be taboo in the Democratic Party to say that it’s time to open up completely and return to work,” he wrote on Twitter last month. “Our economy needs it. New York City’s especially.”

Mr. Rose, a populist Democrat, will instantly be seen as the front-runner in the Democratic primary to take on Ms. Malliotakis. But that, too, is a contested race.

Brittany Ramos DeBarros, who describes herself as an “Afro-Latina Staten Islander, community organizer and progressive combat veteran,” has been fund-raising and locking down some endorsements. She is one of many left-leaning candidates whose campaign logo appears reminiscent of Representative Alexandria Ocasio-Cortez’s.

Ms. Malliotakis, for her part, begins the race bolstered by a favorable national environment for Republicans, even in some corners of New York, and about $1.2 million in cash on hand, according to the most recent campaign filing. She was also one of 13 Republicans to vote for the bipartisan infrastructure bill, which will fund much-needed improvements to subways, roads, bridges and sewers in New York and could assist with general election messaging, though she has also drawn some backlash.

Almost exactly one year ago, Mr. Rose launched an exploratory bid for mayor of New York City before ultimately deciding against a run. But he has remained active on the New York political circuit, attending a Staten Island Democrats event last week and joining Mayor-elect Eric Adams’s transition team.

In the video, Mr. Rose, a decorated combat veteran, cited his military service and his time working as a senior adviser on Covid-19 to the secretary of defense as experiences that gave him hope.

“I’m running because this country, it can be affordable and fair,” he said. “Our politics can lift us up, rather than tear us down. The America we believe in is possible.”

Nicholas Fandos contributed reporting.