NEW YORK (Reuters) - Liberal Democrats on Wednesday said a string of victories in U.S. nominating contests, notably the surprise toppling of powerful congressman Joseph Crowley in New York, proved the party must embrace progressive priorities or face defeat.

But ahead of the November midterm elections and the 2020 presidential race, questions remain about whether the wins signal a permanent leftward shift for the party or resulted from factors specific to those races.

“The best way to excite voters and maximize a wave in 2018 is to run bold, progressive, younger, more diverse candidates who connect authentically with the economic realities of voters - not old-school candidates running establishment campaigns or who are fueled by corporate money,” the Progressive Change Campaign Committee said in a statement, calling the elections a “battle for the heart and soul of the Democratic Party.”

Alexandria Ocasio-Cortez, a 28-year-old political neophyte and former Bernie Sanders organizer running as a democratic socialist, beat Crowley, the No. 4 Democrat in the House, after campaigning in the safely Democratic district on liberal messages like Medicare-for-all.

Nancy Pelosi, the U.S. House of Representatives minority leader, and some fellow Democrats dismissed the notion that the party’s identity was at stake. Asked by reporters in Washington if Crowley’s loss meant democratic socialism was ascendant in the Democratic Party, she said: “It’s ascendant in that district, perhaps.”

Ocasio-Cortez’s campaign framed Crowley’s leadership position as a weakness, taking advantage of the anti-establishment fervor that has animated both Democrats and Republicans in recent years.

“You could make the case that Crowley was more in touch with the inside-the-Beltway D.C. game and House leadership, rather than tending to his garden at home,” said Joshua Henne, a Democratic strategist.

FILE PHOTO: Rep. Joseph Crowley (D-NY), Chairman of the House Democratic Conference, along with Rep. Linda Sanchez (D-CA), speaks at a news conference on Capitol Hill in Washington, DC, U.S., November 29, 2017. REUTERS/Aaron P. Bernstein/File Photo

But, Henne said, the outcome also showed that the insurgent left wing of the party remains its most active force in the era of President Donald Trump and suggested candidates should pursue what he called a “bold progressive agenda.”

“I think the lesson for 2020 is that will bring people out to the polls,” he said.

WARNING SIGNS

There were warning signs for Crowley, a 10-term incumbent who had not faced a challenger from his own party since 2004. He failed to show up for debates with Ocasio-Cortez, fueling her message that the party’s leaders were not paying enough attention to their constituents.

The New York City district he represented has grown increasingly Hispanic, and Democratic women have also outperformed men in primary contests this year.

“You don’t want to run against a Democratic woman this year,” Democratic U.S. Representative John Yarmuth said when asked for his assessment of the race.

Cheri Bustos, an Illinois Democrat seen as a rising star in the party, argued that the Crowley upset did not augur any broader trends.

“I wouldn’t look into this that this is a progressives versus moderates, or a political newcomer versus a long-term incumbent,” she told reporters. “This is a unique race in many, many ways.”

The upset was one of several outcomes that excited liberals on Tuesday, when voters in seven U.S. states chose candidates for the Nov. 6 elections that will determine control of Congress.

In an upstate New York House district, Dana Balter, a professor at Syracuse University, prevailed against Juanita Perez Williams, who was backed by the national party for the Democratic nomination.

In Maryland’s gubernatorial contest, former National Association for the Advancement of Colored People president Ben Jealous defeated Rushern Baker, a local politician supported by most state party officials who ran a more moderate campaign.

Political analysts compared Crowley’s loss to that of Eric Cantor, the Republican House majority leader, who was upset in 2014 by a little-known Tea Party challenger who attacked him from the right.

Douglas Heye, a former Cantor aide, said more liberal Democrats winning elections could stymie the party’s agenda if the party’s split grows, in the same way that hardline Tea Party Republicans have sometimes torpedoed their leadership’s policies in the House.

“This may not lead to further primary upsets, and yes, Crowley ran a lackluster race, and turnout out was low,” he said in an email. “But whether voters meant to send a national message or not, one has been received.”