Zohran Mamdani's upset in New York City's Democratic mayoral primary shocked the political establishment and signaled a generational shift within the party, according to Democrat strategists.Naysayers dismissed the 33-year-old democratic socialist as too young and inexperienced to steer New York City through the uncertainty of President Donald Trump's administration, as Democrats across the country clash with Trump's vision for America and grapple with the party's future after losing the White House and Congress in 2024.Leaning into his democratic socialist values and livestreaming them on social media, Mamdani managed to topple the presumptive front-runner, 67-year-old former Gov. Andrew Cuomo, whom pundits seemed convinced had the funds and name-recognition to pull off a political comeback after leaving office in 2021 amid sexual harassment allegations."It suggests that there's a movement going on in the Democratic Party, especially in terms of age," Brad Bannon, a Democratic strategist and president of Bannon Communications Research, told Fox News Digital.REPUBLICANS USE MAMDANI BOMBSHELL VICTORY OVER CUOMO AS AMMUNITION TO BLAST DEMOCRATS AS EXTREMISTSTrump picked up on the leftward movement, posting on Truth Social Wednesday, "Its finally happened, the Democrats have crossed the line. Zohran Mamdani, a 100% Communist Lunatic, has just won the Dem Primary, and is on his way to becoming Mayor. Weve had Radical Lefties before, but this is getting a little ridiculous."NEW YORK DEMOCRAT SAYS MAYORAL CANDIDATE ZOHRAN MAMDANI 'TOO EXTREME TO LEAD'Stephanie Taylor, co-founder of the Progressive Change Campaign Committee, said in a statement, "Zohran Mamdani's likely victory shows that a new direction for the Democratic Party is possible a future of dynamic candidates who appeal to young voters and working-class voters with a platform that fights for people, not corporations."Mamdani will face off against moderate Democratic Mayor Eric Adams, who has cozied up with Trump and cooperated with the president's crackdown on illegal immigration. Adams won as a Democrat in 2021 but chose to campaign for re-election as an independent, amid low approval ratings and his since-dropped federal corruption charges."Hes a snake-oil salesman," Adams said of Mamdani on "Fox & Friends" Wednesday. "He would say and do anything to get elected."Mamdani's victory Tuesday night prompted Republicans to criticize him as the new face of the party. Freshman Sen. Bernie Moreno, R-Ohio, posted on X, "NYC resident alert: Delta, United, Spirit, and American have daily flights from NYC airports to most Ohio destinations. Leave now before its too late."Mamdani was called every name in the book during his mayoral campaign, from "antisemitic" to "Communist," as Jewish groups and moderate Democrats criticized his radical vision for New York City."But he won anyway. I just think it shows you how much voters want change. I think that's why Trump is president now. Voters are sick of the status quo," Bannon said.On the campaign trail, Mamdani took aim at Cuomo for accepting money from Trump's 2024 presidential campaign donors and framed the race as a referendum on the future of the party, one that "billionaires and corporations want to buy.""It's a question for our own party of: How do we move forward?" Mamdani said on "The Late Show With Stephen Colbert." "Do we move forward with the same politicians of the past, the same policies of the past that delivered us this present, or do we move forward with a new generation of leadership, one that is actually interested in serving the people?"Progressive Democrats rallied behind Mamdani as he worked to consolidate support within the ranked choice voting style by cross-endorsing with New York City Comptroller Brad Lander. Mamdani and Lander campaigned together in the weeks leading up to primary day.Mamdani secured endorsements from Sen. Bernie Sanders, I-Vt., the democratic socialist national leader and two-time Democratic presidential nominee runner-up, and New York Democratic star Rep. Alexandria Ocasio-Cortez, who unseated a longtime incumbent in 2018.As Ocasio-Cortez campaigned with Mamdani online and in New York City, fellow "Squad" members also rallied behind Mamdani, endorsing his campaign from afar, including Reps. Rashida Tlaib, D-Mich., and Rep. Ilhan Omar, D-Minn., who congratulated his win Tuesday night.The democratic socialist described his vision for New York Citys future as a place "where the mayor will use their power to reject Donald Trump's fascism, to stop mass ICE agents from deporting our neighbors and to govern our city as a model for the Democratic Party." Mamdani has proposed radical ideas, like government-run grocery stores, free bus service, tuition-free city universities, rent freezes and free childcare, among other ideas."As a fellow millennial, Im thrilled to see voters rally behind a joyful, people-powered campaign rooted in love for the city. Voters spoke clearlyand they chose a bold, hopeful future," Democratic National Committee (DNC) vice chair Malcolm Kenyatta celebrated Tuesday night.David Hogg, the former DNC vice chair who was ousted after a procedural challenge to his leadership position after stirring up intraparty division for his plan to primary older incumbent Democrats he said were "asleep at the wheel," campaigned for Mamdani in New York City ahead of the primary.Hogg celebrated Mamdani's victory in a series of posts Tuesday night, emphasizing of Cuomo's concession, "Crazy idea - maybe we should stop running the same people who brought our party to this place."But the old-guard of the Democratic Party seemed more reluctant to embrace this radical change and leftward shift as Senate Minority Leader Chuck Schumer, D-N.Y., refused to answer reporters' follow-up questions Wednesday about what Mamdani's win signals for the Democratic Party."He ran an impressive campaign that connected with New Yorkers about affordability, fairness, & opportunity. I spoke with @ZohranKMamdani this morning and am looking forward to getting together soon," Schumer said on X.Meanwhile, Bannon pointed to California Democratic Rep. Robert Garcia's leadership nomination on the House Oversight Committee Tuesday, calling the progressive shift "generational.""Democrats anointed a guy who was 25 years younger and had less experience on the committee. So, I think you're seeing it all over the place, and I think that you're going to see more," Bannon added.Fox News' Paul Steinhauser and Kelly Phares contributed to this report.