(CNN) Hillary Clinton declared victory early Tuesday morning in a razor-thin contest against Bernie Sanders in Iowa. But Democratic party officials have not yet declared a winner.

"Hillary Clinton has won the Iowa Caucus," the Clinton campaign said. "After thorough reporting -- and analysis -- of results, there is no uncertainty and Secretary Clinton has clearly won the most national and state delegates."

The state party indicated in a separate statement that it was not ready to make a call.

"The results tonight are the closest in Iowa Democratic caucus history," Iowa party chairman Andy McGuire said. "We will report that final precinct when we have confirmed those results with the chair."

One thing is clear after Monday night's Iowa caucuses: there's a long, volatile election season ahead before two deeply fractured parties can unite behind a nominee.

Photos: Moments from Ted Cruz's career Photos: Moments from Ted Cruz's career U.S. Sen. Ted Cruz, a Republican presidential candidate, speaks during a campaign rally at the Indiana State Fairgrounds on Monday, May 2. Hide Caption 1 of 24 Photos: Moments from Ted Cruz's career Cruz holds up the hand of Carly Fiorina at a campaign rally in Indianapolis on Wednesday, April 27. Cruz named Fiorina, a former presidential candidate, as his running mate. Hide Caption 2 of 24 Photos: Moments from Ted Cruz's career Cruz celebrates his Wisconsin primary win with his wife, Heidi, and Gov. Scott Walker in Milwaukee on Tuesday, April 5. Walker endorsed Cruz for the presidency. Hide Caption 3 of 24 Photos: Moments from Ted Cruz's career With his wife by his side, Cruz tours the Dane Manufacturing facility before speaking to workers in Dane, Wisconsin, on Thursday, March 24. Hide Caption 4 of 24 Photos: Moments from Ted Cruz's career Cruz speaks during the CNN Republican debate in Miami on Thursday, March 10. Hide Caption 5 of 24 Photos: Moments from Ted Cruz's career Cruz and his wife wave to the crowd at Liberty University after he announced his presidential candidacy in Lynchburg, Virginia, on March 23, 2015. Hide Caption 6 of 24 Photos: Moments from Ted Cruz's career Cruz speaks during the 2013 NRA Annual Meeting and Exhibits at the George R. Brown Convention Center on May 3, 2013, in Houston, Texas. Hide Caption 7 of 24 Photos: Moments from Ted Cruz's career Cruz poses with his wife, Heidi, and his daughters Caroline and Catherine. Hide Caption 8 of 24 Photos: Moments from Ted Cruz's career Cruz (left) fields questions from Bruce Rastetter at the Iowa Ag Summit on March 7, 2015, in Des Moines, Iowa. The event allows the invited speakers, many of whom are potential 2016 Republican presidential hopefuls, to outline their views on agricultural issue. Hide Caption 9 of 24 Photos: Moments from Ted Cruz's career Nobel Peace Laureate Elie Wiesel (left) listens as Cruz (right) speaks during a roundtable discussion on Capitol Hill March 2, 2015 in Washington, D.C. Wiesel, Cruz and Rabbi Scmuley Boteach (center) participated in a discussion entitled 'The Meaning of Never Again: Guarding Against a Nuclear Iran.' Hide Caption 10 of 24 Photos: Moments from Ted Cruz's career Governor Greg Abbott (center) speaks alongside Cruz (left), Attorney General Ken Paxton (right) at a joint press conference February 18, 2015, in Austin, Texas. Hide Caption 11 of 24 Photos: Moments from Ted Cruz's career Sen. Patrick Leahy (right) escorts Loretta Lynch back from a lunch break as Cruz (left) sits nearby during her confirmation hearing before the Senate Judiciary Committee January 28, 2015, on Capitol Hill. Hide Caption 12 of 24 Photos: Moments from Ted Cruz's career Cruz greets supporters at the South Carolina Tea Party Coalition convention on January 18, 2015, in Myrtle Beach, South Carolina. A variety of conservative presidential hopefuls spoke at the gathering on the second day of a three-day event. Hide Caption 13 of 24 Photos: Moments from Ted Cruz's career Cruz (left) and then-Texas Governor Rick Perry stand together during a press conference at the front gate of Fort Hood about Iraq war veteran, Ivan Lopez, who killed three and wounded 16 before taking his own life on April 4, 2014, in Fort Hood, Texas. Hide Caption 14 of 24 Photos: Moments from Ted Cruz's career (Left to right) Sen. Lindsey Graham, Sen. John McCain and Cruz listen as President Barack Obama delivers the State of the Union address on January 28, 2014, in Washington, D.C. Hide Caption 15 of 24 Photos: Moments from Ted Cruz's career Then-Senate Minority Leader Mitch McConnell (second right), poses with Republican senators-elect Jeff Flake (left), Deb Fischer (second left), and Cruz (right) at the U.S. Capitol on November 13, 2012, in Washington, D.C. Hide Caption 16 of 24 Photos: Moments from Ted Cruz's career Cruz speaks to reporters on September 25, 2013, after ending his talk-a-thon on the floor of the US Senate in Washington, D.C. Hide Caption 17 of 24 Photos: Moments from Ted Cruz's career Cruz speaks as then-Rep. Michele Bachmann (left), Sen. Mike Lee (second right) and Sen. Rand Paul (right) listen during a news conference May 16, 2013, on Capitol Hill. Hide Caption 18 of 24 Photos: Moments from Ted Cruz's career Cruz listens to testimony during a Senate Judiciary Committee hearing on April 22, 2013, in Washington, D.C. Hide Caption 19 of 24 Photos: Moments from Ted Cruz's career Cruz holds a news conference to announce the plan to defund Obamacare on March 13, 2013. Hide Caption 20 of 24 Photos: Moments from Ted Cruz's career Cruz speaks at the CPAC on March 6, 2014, in National Harbor, Maryland. Hide Caption 21 of 24 Photos: Moments from Ted Cruz's career Then-Senate Republican Candidate and Texas Solicitor General Cruz speaks at the 'Patriots for Romney-Ryan Reception' on August 29, 2012, in Tampa, Florida. Hide Caption 22 of 24 Photos: Moments from Ted Cruz's career Then-Senate Republican Candidate and Texas Solicitor General Cruz speaks during the Republican National Convention at the Tampa Bay Times Forum on August 28, 2012. Hide Caption 23 of 24 Photos: Moments from Ted Cruz's career Then-Senate Republican Candidate and Texas Solicitor General Cruz speaks during the Republican National Convention in 2012. Hide Caption 24 of 24

Cruz's victory sets him up as a formidable force in delegate-rich, Southern states to come and offers movement conservatives hope that one of their own can become the Republican nominee for the first time since Ronald Reagan.

Claiming victory, Cruz fired immediate shots at both Trump and the party elites he has so infuriated by waging an anti-establishment crusade that has nevertheless endeared him to the GOP's rank and file.

"Iowa has sent notice that the Republican nominee and the next President of the United States will not be chosen by the media, will not be chosen by the Washington establishment," Cruz said.

With about 99% of the GOP vote in, Cruz was ahead of Trump 28% to 24%. Rubio was at 23%.

"It is breathtaking to see what happens when so many Americans stand up and decide they're fed up with what happens in Washington and they want something different. They want a leader they can trust, they want a leader that stands for them against the corruption of Washington," Cruz told CNN's Dana Bash in an interview aired Tuesday on "New Day."

Trump, hours after predicting a "tremendous" victory, delivered a short but gracious speech that lacked his normal bombast, saying he loved Iowa and vowed to bounce back next week in New Hampshire.

"We will go on to get the Republican nomination and we will go on to easily beat Hillary or Bernie," Trump told supporters. "We finished second, and I have to say I am just honored."

Rubio will also leave Iowa with a leg up over other establishment rivals including former Florida Gov. Jeb Bush, New Jersey Gov. Chris Christie and Ohio Gov. John Kasich, who have a lot at stake in New Hampshire.

"This is the moment they said would never happen. For months, they told us we had no chance," a jubilant Rubio said. "They told me that I needed to wait my turn, that I needed to wait in line. But tonight here in Iowa, the people of this great state have sent a very clear message — after seven years of Barack Obama, we are not waiting any longer to take our country back."

Photos: Iowa caucuses kick-start presidential race U.S. Sen. Ted Cruz emerges victorious at a rally Monday, February 1, in Des Moines after taking first place in Iowa's Republican caucuses on Monday, February 1. With about 99% of precincts reporting, Cruz had 28% of the vote, compared with 24% for Donald Trump and 23% for U.S. Sen. Marco Rubio. "Iowa has sent notice that the Republican nominee and the next president of the United States will not be chosen by the media, will not be chosen by the Washington establishment," Cruz said. Hide Caption 1 of 19 Photos: Iowa caucuses kick-start presidential race With former President Bill Clinton and daughter Chelsea at her side, Democratic presidential candidate Hillary Clinton addresses supporters February 1 at Drake University in Des Moines. The following morning, the Clinton campaign declared victory in the razor-thin contest against Sen. U.S. Bernie Sanders. "Hillary Clinton has won the Iowa caucus," the Clinton campaign said. "After thorough reporting -- and analysis -- of results, there is no uncertainty and Secretary Clinton has clearly won the most national and state delegates." The Iowa Democratic Party indicated in a separate statement it was not ready to make a call. Hide Caption 2 of 19 Photos: Iowa caucuses kick-start presidential race Sanders and his wife, Jane, acknowledge the crowd as he arrives for his caucus night rally in Des Moines. "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," Sanders said. "And tonight, while the results are still not known, it looks like we are in a virtual tie." Hide Caption 3 of 19 Photos: Iowa caucuses kick-start presidential race Trump gives supporters the thumbs-up as he concedes defeat in Des Moines. Trump vowed to win next week's New Hampshire primary. "We will go on to get the Republican nomination, and we will go on to easily beat Hillary or Bernie," Trump said. "We finished second, and I have to say I am just honored." Hide Caption 4 of 19 Photos: Iowa caucuses kick-start presidential race Rubio addresses his supporters at a caucus night rally in Des Moines. "This is the moment they said would never happen," Rubio said. "For months, they told us we had no chance. They told me that I needed to wait my turn, that I needed to wait in line. But tonight here in Iowa, the people of this great state have sent a very clear message: after seven years of Barack Obama, we are not waiting any longer to take our country back." Hide Caption 5 of 19 Photos: Iowa caucuses kick-start presidential race Clinton supporters in Des Moines watch the television as caucus results roll in. Hide Caption 6 of 19 Photos: Iowa caucuses kick-start presidential race Trump supporters attend a watch party in West Des Moines. Hide Caption 7 of 19 Photos: Iowa caucuses kick-start presidential race A Sanders supporter celebrates caucus results at a Des Moines precinct. Hide Caption 8 of 19 Photos: Iowa caucuses kick-start presidential race Republican voters sing the national anthem in the gymnasium of an elementary school in Adel, Iowa. Hide Caption 9 of 19 Photos: Iowa caucuses kick-start presidential race Paper ballots are counted at a middle-school auditorium in Des Moines. Hide Caption 10 of 19 Photos: Iowa caucuses kick-start presidential race A Rubio supporter holds a sign at a caucus site in Clive, Iowa. Hide Caption 11 of 19 Photos: Iowa caucuses kick-start presidential race Sanders watches caucus returns at his hotel room in Des Moines. Hide Caption 12 of 19 Photos: Iowa caucuses kick-start presidential race People sign in as they arrive at a Democratic Party caucus in Keokuk, Iowa. Hide Caption 13 of 19 Photos: Iowa caucuses kick-start presidential race Iowans register to cast their ballot in Ames. Hide Caption 14 of 19 Photos: Iowa caucuses kick-start presidential race Caucus workers check in voters prior to a Republican Party caucus in Keokuk. Hide Caption 15 of 19 Photos: Iowa caucuses kick-start presidential race The shadows of lined-up caucusgoers are seen outside a school in West Des Moines. Hide Caption 16 of 19 Photos: Iowa caucuses kick-start presidential race Clinton poses for selfies at her campaign office in Des Moines. Hide Caption 17 of 19 Photos: Iowa caucuses kick-start presidential race Trump pauses for a selfie while visiting the St. Francis of Assisi Church, a caucus site in West Des Moines. Hide Caption 18 of 19 Photos: Iowa caucuses kick-start presidential race Cruz speaks earlier in the day at the Green County Community Center in Jefferson, Iowa. Hide Caption 19 of 19

On the Democratic side, Clinton and Sanders are deadlocked at 50% with 99% of the votes counted. Clinton, the national front-runner, admitted breathing a "big sigh of relief" after escaping Iowa -- the state she handily lost to Obama in 2008 -- but promised a vigorous campaign with Sanders.

"It's rare that we have the opportunity we do now," she said in a speech that didn't explicitly claim victory but sought to position her as the authentic progressive in the race.

Sanders, who trailed Clinton in Iowa by 30 points three months ago, told a raucous crowd chanting "Bernie, Bernie" that his campaign made stunning progress.

"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."

"And tonight," he said, "while the results are still not known, it looks like we are in a virtual tie."

Though Sanders fared well in Iowa and is nicely posited in New Hampshire, his hurdle is proving that he can appeal to more ethnically diverse electorates in later contests in places such as South Carolina.

Sanders made the case to CNN's Chris Cuomo, when he campaign plane landed in New Hampshire early on Tuesday morning, that he expects to challenge Clinton among nonwhite voters.

"We lost (the nonwhite vote), but that gap is growing slimmer and slimmer between the secretary and myself. I think you'll find as we get to South Carolina and other states, that when the African-American community, the Latino community, looks at our record, looks at our agenda, we're going to get more and more support," Sanders told Cuomo on "New Day."

The caucuses resulted in two casualties -- one on each side. Former Maryland Gov. Martin O'Malley, a Democrat, and former Arkansas Gov. Mike Huckabee, a Republican, both dropped their candidacies after faring poorly.

Even before the caucuses began, Ben Carson's campaign said he wouldn't go directly to New Hampshire or South Carolina -- the site of the next primary contests. Instead, the retired neurosurgeon, who was briefly the Iowa front-runner last fall, will go to Florida to rest and see his family.

Former Pennsylvania Sen. Rick Santorum is also skipping New Hampshire but will go straight to South Carolina, which holds its Republican presidential primary on February 20.