One week to go, the 2016 presidential candidates opened their final push Monday in Iowa, seeking any edge in a race brimming with unpredictability for both Democrats and Republicans.

Hillary Clinton and Bernie Sanders, locked in an unexpectedly tight race, planned to deliver their final-stretch pitches Monday evening in a televised town hall forum, while President Barack Obama delivered his own blunt assessment of their contest. Obama praised Sanders for energizing liberals while saying that Clinton’s perceived dominance in the race had been both an advantage and a burden.

Republicans who have spent months courting Iowans were working to ensure their supporters make it to the caucuses next Monday that mark the start of presidential primary voting. With insurgent candidates Donald Trump and Ted Cruz battling for victory in Iowa, the remaining GOP contenders are hoping that a better-than-expected performance can provide a momentum boost heading into New Hampshire, where the Feb. 9 primary will provide the best opportunity for an alternative to the front-runners to rise.

Adding a new flavor of uncertainty was word over the weekend that former New York Mayor Michael Bloomberg is considering an independent bid, eyeing an opportunity if Trump and Sanders should end up as the Republican and Democratic nominees. Bloomberg’s assessment of the race underscores concerns in both parties about whether they can win a general election with outside-the-box candidates like Sanders and Trump.

Obama, in an interview with Politico, praised Clinton as "wicked smart" but said she faced enormous expectations that had taught her to be more cautious. Carefully avoiding the appearance of favoritism in the race, Obama said Sanders had clearly tapped into many Democrats’ hunger for a candidate who speaks bluntly and loudly about liberal values.

"You know, that has an appeal," Obama said. "And I understand that."

Clinton’s campaign sought to revive a debate about gun control, building on her previous criticism of Sanders’ record of backing legislation granting gun manufacturers legal immunity. With the Vermont senator insisting he’s been a consistent gun safety supporter, Clinton’s team dispatched a prominent gun control advocate to deride his "disgraceful record."

"We are all less safe as a result," said Dan Gross, president of the Brady Campaign to Prevent Gun Violence.

Sanders, who has been on an aggressive Iowa tour in the final days, returned his focus to his plan for government-run health care. Clinton has warned that Sanders’ proposal risks jeopardizing the progress made with Obama’s Affordable Care Act. But Sanders sought to give the issue a personal face Monday, turning the microphone over to supporters who told stories about poverty and struggling to afford medicine.

"You’re ashamed all the time," said Carrie Aldrich, 46, who teared up as she told Sanders about living on less than $10,000 a year as she struggles with a disability. "When you can’t buy presents for your children, it’s really, really hard."

For Republicans, the close contest between Cruz and Trump for first place reflects a growing if grudging acceptance among GOP leaders that one of the two may be the party’s nominee. Party leaders worry that having such a provocative candidate will alienate voters the GOP needs to win in November, potentially risking both the White House and down-ballot races.

Also drawing intense interest in Iowa is the competition for third, where Marco Rubio’s campaign received a boost over the weekend with the endorsement of the state’s largest newspaper. Rubio and the others vying for third hope to get a fresh look after Iowa to position themselves as a safer choice for the party.

Cruz picked up an endorsement Monday from Rick Perry, his home state former governor who dropped out of the presidential race last year. Rubio also won, if not an official endorsement, a glowing introduction from the state’s freshman Republican Sen. Joni Ernst, a popular figure in the Iowa GOP who called him "near and dear" to her heart.

With most of the Republicans circling each other in Iowa, Chris Christie and John Kasich were searching for votes in New Hampshire, where the GOP base is friendlier to more mainstream, socially moderate candidates. Speaking to reporters in Newmarket, Kasich seemed to capture the mood of all of the candidates many months into a grueling campaign.

"I think there’s so many undecided people, and I wish they were all committed to me," Kasich said. "What am I not doing right?"

(Copyright (c) 2016 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)

Join our Newsletter for the latest news right to your inbox