Former Secretary of State Hillary Clinton speaks to Iowa voters at a campaign event in Clinton, Iowa on Saturday, January 21, 2016. (Photo by Melina Mara/The Washington Post)

Just over a week ahead of the Iowa caucuses, Hillary Clinton and Marco Rubio won the party endorsements of the Des Moines Register on Saturday, securing one of the most coveted and hard-fought political prizes of the presidential calendar.

Both Clinton, the Democrat, and Rubio, the Republican, are polling behind other candidates in most recent Iowa public opinion surveys. In each case, the state’s largest and most influential newspaper said their chosen candidates had something the others lacked. For Clinton, it was her experience that won her the endorsement; for Rubio, his ideas and potential.

“Democrats have one outstanding candidate deserving of their support: Hillary Clinton,” the Register editorial board wrote. “No other candidate can match the depth and breadth of her knowledge and experience.”

Clinton met with the board several times, sitting for lengthy interviews that covered her domestic priorities, foreign affairs and matters of Iowa concern such as federal ethanol subsidies. The former secretary of state made news in her first televised Des Moines Register interview by saying that she opposed the Keystone XL pipeline.

“In the final analysis, Iowa Democrats will have to choose between the lofty idealism of Bernie Sanders and the down-to-earth pragmatism of Hillary Clinton. For some, this will be a choice of whether to vote with their hearts or their heads,” the board wrote.

“Clinton has demonstrated that she is a thoughtful, hardworking public servant who has earned the respect of leaders at home and abroad. She stands ready to take on the most demanding job in the world.”

The newspaper charted Clinton’s long political career and said she has amassed the record and expertise to handle the complex and varied requirements of the Oval Office.

“The presidency is not an entry-level position. Whoever is sworn into office next January must demonstrate not only a deep understanding of the issues facing America, but also possess the diplomatic skills that enable presidents to forge alliances to get things done,” the newspaper wrote.

Clinton’s campaign immediately trumpeted the endorsement, which comes as she battles a late and surprisingly strong insurgent challenge from Vermont independent Sen. Sanders.

Clinton will campaign in Iowa on Sunday and most of next week ahead of the Feb. 1 caucuses. A loss in Iowa would evoke the crippling loss she suffered there in 2008 and call into question the revamped strategy she has employed there this time.

“Sen. Marco Rubio has the potential to chart a new direction for the party, and perhaps the nation, with his message of restoring the American dream,” the newspaper tweeted. “We endorse him because he represents his party’s best hope.”

In its endorsement of the Florida Republican, the Register's editorial board seemed to be rejecting the more irate brand of politics espoused by Donald Trump.

"Republicans have the opportunity to define their party’s future in this election. They could choose anger, pessimism and fear. Or they could take a different path," the board wrote. "The party could channel that frustration and pursue true reform. It could renounce its fealty to the economic elite and its fixation with tax cuts for the wealthy."

The endorsement is welcome news for Rubio, who is a distant third in the polls behind Trump and Sen. Ted Cruz (R-Tex.), the party's two front-runners in Iowa.

At a town hall in Indianola, Iowa on Saturday night, a man congratulated Rubio on winning the Register's backing.

"I'd rather have your endorsement," Rubio responded. He added that he is "grateful" for the Register's endorsement but, "I still want you to caucus for me."

As supporters and aides started filing into the town hall, a staffer could be heard excitedly talking about the endorsement.

"Not a bad one to get," he said.

Even as the board backed Rubio, it said there are plenty of questions about him, including whether his ambition will trump his optimism. The board also said it wished he attended more votes in the Senate, a frequent criticism of his rivals.

Sullivan reported from Indianola, Iowa