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Democratic presidential candidate Sen. Bernie Sanders (I-VT) smiles as he speaks to supporters during a caucus night party Feb. 1, 2016 in Des Moines, Iowa. alex wong/getty images

Bernie Sanders isn’t going anywhere. That was the message the Vermont senator sent to supporters — and to the establishment — as he declared an ideological victory in Iowa late Monday night, despite the results being too close to call.

The Vermont senator has run an insurgent campaign against Hillary Clinton, and Iowa marked the first test for whether the enthusiasm Sanders has seen at rallies and on social media could translate into real votes. Sanders and the former secretary of state were virtually tied in the Iowa caucuses Monday night, with both candidates declaring victory in dueling speeches while the Democratic Party counted the remaining votes.

For Sanders, the extremely close results in the Hawkeye State were proof that his grassroots style of campaigning is not only viable, but that it could be a significant problem for Clinton going forward. The senator gave a victory-style speech Monday night, telling his supporters that their near-tie in Iowa represented a referendum on the inevitability of Clinton, who was once considered the prohibitive front-runner.

“I think the people of Iowa have sent a very profound message to the political establishment, to the economic establishment and by the way to the media establishment,” Sanders said in a speech to his supporters in Des Moines Monday night. “That is given the enormous crises facing our country, it is just too late for establishment politics and establishment economics.”

Though the high level of support for Sanders was expected to propel him forward going into the New Hampshire primary election next week, it will be the contests after the Granite State that prove a more difficult test for the Vermont senator. As he continues to compete against Clinton, he will need to widen his base of support and woo minority voters if he wants to win in more diverse states such as Nevada, South Carolina and the group of states that vote March 1.

One of the main concerns about Sanders’s candidacy has been his narrow path to the nomination. While he did well in Iowa, it was a state that many said should have been relatively easy for the senator to win given its very white, very liberal composition. Sanders has relied heavily on young voters and independents, who are also prevalent in the state.

New Hampshire, where he is thought to have a near-home state advantage, has a fairly similar composition to Iowa, so Sanders will need to win there as well to keep his momentum going. Clinton has often tried to paint Sanders as a candidate with regional appeal, and his lack of a decisive victory in Iowa does not help push back on that narrative as much as he might have hoped.

The most recent polls in New Hampshire have had Sanders leading Clinton by double digits, but in South Carolina and other Southern states, Clinton typically sits around 30 points up on Sanders. Now that Iowa is behind him, Sanders will likely turn more attention to the late February and March votes as his campaign readies for a months-long contest.

In his speech in Iowa Monday night, Sanders discussed his major campaign issues including campaign finance reform, single-payer health care and raising the minimum wage, but he also made sure to include a criticism of the nation’s incarceration rates — an appeal to criminal justice issues that are particularly important to minority voters and activists.

Despite the uphill battle that the senator still faces, the extremely close race in the first-in-the-nation state was indicative of how Sanders has surprised the Clinton campaign with his viability this election season. He has eschewed big money donations from super PACs, while gaining on her not only in Iowa and New Hampshire, but also nationally.

His campaign has continued to remind supporters of how it began with very few resources and upended establishment expectations, a theme Sanders stuck to Monday night.

“Nine months ago we came to this beautiful state, we had no political organization, we had no money, we had no name recognition, and we were taking on the most powerful political organization in the United States of America,” the Vermont senator shouted Monday.

Throughout the campaign, Sanders has managed to capitalize on social media enthusiasm to fundraise huge sums, and he was expected to gain a large bump in both polls and money after Monday night. Sanders announced during his speech Monday that he has received 3.5 million individual contributions so far. He raised more than $20 million in January alone, an enormous sum given the average contribution size was $27. Clinton, meanwhile, has also raised massive amounts of money after losing Iowa to President Barack Obama eight years ago — she brought in $112 million in 2015, CNN reported, and has $10 million more on hand than Sanders as the two move forward.

In the hours leading up to the Iowa caucuses, Sanders was by far the most discussed candidate on Facebook, according to data from the social network. Sanders dominated 42 percent of the conversation about the Iowa caucuses, and 73 percent of the conversation about Democrats, Facebook data earlier Monday showed.

Both Clinton and Sanders had sent out fundraising emails to supporters thanking them for their showing in Iowa even before results were announced early Tuesday morning. After the Democratic candidates made their speeches, both were expected to head to New Hampshire, where they will spend much of the next week as they look to move on to the next contest.

They will face off in a town hall in New Hampshire Wednesday night, just days ahead of the first-in-the-nation primary election, giving people another chance to hear from the candidates before casting their votes.