PARIS - President Francois Hollande’s Socialist Party coasted to a comfortable majority in France’s parliamentary elections Sunday, virtually guaranteeing passage of his measures to reinvigorate the economy and help the poor more easily weather Europe’s debt crisis.

The Socialist victory, complementing Hollande’s election as president in May, avoided the deadlock that would have occurred had a blocking majority gone to the conservative Union for a Popular Movement, the coalition of former president Nicolas Sarkozy.

France’s Socialists will have between 308 and 320 seats in the 577-seat National Assembly after Sunday’s second-round parliamentary elections, the TNS-Sofres Sopra Group, Ipsos, and CSA agencies estimated. The projections were based on actual vote counts in districts across the nation.

The total is well above the 289 the Socialists needed for a majority, and it means they will not have to rely on far-leftists who oppose some of Hollande’s pro-European policies to pass legislation.

The new Parliament will lean well left: the Socialists and allied parties, the Greens, and the Leftist Front parties are estimated to have won 340 to 350 seats combined. Sarkozy’s UMP and its allies are estimated to have between 213 and 221 seats.

Reinforcing Hollande’s authority at home, the majority strengthens his hand in tense negotiations with Germany over ways to relieve pressure against the euro, the common currency of 17 European nations.

“This evening there is a new parliamentary majority in France that conforms to the presidential majority,’’ declared Foreign Minister Laurent Fabius, a veteran Socialist leader. “This new, solid and large majority will allow us now to pass laws for change, and gives us great responsibilities in France and in Europe.’’

Socialists already control the Senate. In campaigning for the lower house, Hollande’s followers used the threat of a legislative standoff with the conservatives to motivate voters despite a lackluster campaign that touched only marginally on the pressing economic issues facing France and the European Union.

While deficits and debt were little dealt with, public attention focused heavily on a made-in-France contest between rival Socialists in La Rochelle that unfurled more like a soap opera than a political campaign.

The winning candidate was Olivier Forlani, a Socialist dissident who had refused to step aside for the candidate named by the Socialist leadership in Paris. That candidate, who suffered from accusations she was “parachuted’’ into the Atlantic coast city, was Segolene Royal, who lived with Hollande for years and had four children with him before an unsuccessful run for president in 2007.

With opinion polls showing Royal in trouble despite her national stature, Hollande last week issued a message of support, violating a campaign pledge to remain above party politics. When she learned of the gesture, Valerie Trierweiler, a journalist who lives with Hollande and serves as the unmarried first lady, tweeted a message supporting Forlani.

Trierweiler’s message was widely interpreted as spiteful and inappropriate, including by Prime Minister Jean-Marc Ayrault, and Royal said she was “wounded’’ and “bruised’’ when she heard of it. It was also taken as a display of friction in Hollande’s personal life, despite his pledge to introduce sobriety and reserve into the presidency.

Hollande has said his first priorities for the new Parliament include postponing a balanced budget until 2017, raising income taxes to 75 percent for those who earn more than $1.26 million a year, and hiring 60,000 teachers.

France is the second-largest economy in the eurozone and, along with powerhouse Germany, contributes heavily to bailouts for weaker nations and often drives EU-wide policy.