Moderate Democrats increased their numbers and clout after winning in competitive districts this week. These victories helped the party seize control of both chambers of Congress. Elaine Luria said, "It is clear that it is moderates in these swing districts who flipped the House." Centrist groups got much larger now.

Victories by moderates in competitive or Republican-leaning states and districts paved the way for large new Democratic majorities likely to be shaped by their priorities.

For much of the midterm campaign, progressive Democratic insurgents commanded the spotlight in the fight to wrest control of Congress, defeating establishment incumbents in primaries, drawing enthusiastic crowds and promising to reorder their party's priorities and remake American politics once they got to Washington.

But the path to Democrats' sweeping victory this week, when they seized control of both chambers of Congress, was paved overwhelmingly by moderates who had spent months persuading voters in Republican-leaning states and competitive congressional districts that they could be trusted to govern and would deliver dissatisfied voters a practical alternative to President Trump.

Their success has fundamentally altered the balance of power among Democrats in Congress, handing Representative Hakeem Jeffries, the presumptive next speaker, and Senator Chuck Schumer, the would-be majority leader -- both New York moderates viewed with disdain by the left -- majorities built around lawmakers who campaigned not as left-wing heroes but as pragmatic populists. They promised to lower costs, improve health care and restore trust in government, not necessarily to deliver the sweeping transformations championed by the party's ascendant liberals.

For Mr. Jeffries, himself a centrist who has long balanced competing factions of his caucus, the arrival of more moderate Democrats could strengthen his hand in setting an agenda focused on economic relief and achievable legislative victories. But it also sets up a potential confrontation with progressives who helped energize the party's base and now expect their own priorities to be reflected in the new majority's agenda.

"It is clear that it is moderates in these swing districts who flipped the House, who put the gavel in the hand of every committee chair and the speaker," Elaine Luria, one such Democrat who reclaimed a House seat in Virginia that she lost four years ago, said in an interview.

The scale of moderate gains was reflected in the growing ranks of the centrist groups on Capitol Hill. The Blue Dog Coalition, a caucus of moderate and conservative Democrats in the House, announced on Wednesday that it had added at least 14 to its ranks, nearly doubling in size, and other centrist groups including the New Democrats and Problem Solvers strengthened their numbers substantially.

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