In Iowa, Hillary Clinton's campaign is scrubbing dishes, handwriting notes and organizing group yoga. But will its efforts get supporters to caucus for her early next year? The Times' Evan Halper and Noah Bierman traveled to the state recently and found a landscape where Clinton has amassed organizational strength but has yet to lock down a win.

Ben Carson, the retired neurosurgeon, appears to be the latest presidential candidate to go through the cycle of taking the field by surprise, undergoing a tougher examination, then starting to fade.

In recent weeks, Carson has dealt with recurring doubts about his celebrated biographical story. He's also stumbled over questions about his policy positions on healthcare, foreign policy and taxes.

For a while, nothing seemed to stop his rise in the polls, particularly in Iowa, where he has strong appeal to the state's large number of evangelical Christian voters.

But, as has happened with many candidates before him, gravity appears to be having its effect.

The last four polls in Iowa show Carson dropping by about 10 points in that state and ceding first place back to Donald Trump, who has relentlessly questioned the authenticity of Carson's story of his youth.

In New Hampshire, where he was never as strong, Carson has fallen to a tie for fourth place in the latest Fox News poll, behind Trump and Sens. Ted Cruz and Marco Rubio.

Nationally, Carson has also declined in several recent surveys.

With more than two months before the first votes are cast, Carson still has plenty of time to recover and a strong base among religious voters. But the example of previous campaigns offers little reassurance for him: The sudden arc up, followed by an equally abrupt decline is the usual pattern for presidential hopefuls who seemingly come out of nowhere.

Sen. Ted Cruz is harnessing the power of prayer for his presidential bid.

The Texas Republican is creating a National Prayer Team that will hold a weekly prayer conference call every Tuesday as part of Cruz’s strategy to tap into the enthusiasm of evangelical voters, particularly those in the early Southern primary states.

“We’re organizing 'A Time for Prayer' to establish a direct line of communication between our campaign and the thousands of Americans who are lifting us up before the Lord,” Cruz said.

Those who sign up to join the team will also receive weekly emails with prayer requests for the nation and the candidate. And it will also provide the Cruz campaign with a fresh email list of the potential small-dollar donors who have fueled his war chest.

Cruz has positioned himself as the most conservative candidate in the Republican field, and his team seeks to stretch the senator’s appeal beyond his tea party base to a wider conservative audience.

Evangelical voters are a powerful bloc, and they have the potential to have oversized influence on March 1, when several Southern states will vote in what’s been dubbed the SEC primary, after the college athletic conference.

The Cruz campaign’s goal is for the senator to become the right flank’s top choice in a matchup with the establishment-backed favorite in a final showdown for the party’s nomination.

Criticizing Ben Carson’s foreign policy knowledge has cost his longtime business manager a position with the campaign. Carson severed ties with Armstrong Williams after Williams told Bloomberg TV on Tuesday that Carson is on a learning curve with understanding foreign policy.

"There's much for him to learn,” Williams said in the interview. "He's not perfect, he will be perfect but he continues to surround himself with people who will enhance his foreign policy credentials."

Williams had appeared several times on media outlets to speak about Carson’s candidacy. But on Thursday, Carson told reporters in Alabama that Williams does not speak for his campaign.

"He has nothing to do with the campaign. Nothing," Carson said. "Armstrong can comment on his own behalf."

The two men started working together and calling each other to talk about politics more than a decade ago, Williams previously told CNN. Many viewed Williams as an important advisor for Carson.

Donald Trump would “absolutely” implement a database to track Muslims in the United States, he said in an interview with NBC News on Thursday in Iowa, doubling down on his earlier assertion that he'd consider such a program.

The GOP candidate voiced his plans to monitor Muslims and even close certain mosques in response to the terror attacks in Paris that killed 129 people last week.

"I would certainly implement that. Absolutely," Trump said in Iowa. "There should be a lot of systems, beyond databases," he added. "We should have a lot of systems."

This came after he told Yahoo News that some mosques will need to close.

Some of his Republican rivals disavowed Trump's comments as pandering and at odds with American values.

Jeb Bush called Trump’s idea to register Muslims “just wrong” in an interview with CNBC on Friday. Bush said candidates can’t abandon the value of freedom in the race to the presidency or in an effort to take down terrorists.

"It’s not a question of toughness. It’s manipulating people's angst and their fears. That’s not strength. That’s weakness," Bush said.

Critics of Trump’s comments compared his plan to the Nazis' systematic roundup of Jews as well as the Japanese internment camps in the U.S. during World War II. In an interview with NBC News, the national spokesman for the Council on American-Islamic Relations, Ibrahim Hooper, said he had no words for Trump.

"What else can you compare this to except to prewar Nazi Germany?" Hooper said. "There's no other comparison, and he seems to think that's perfectly OK."

On Thursday, a super PAC for Ohio Gov. John Kasich launched new ads against Trump, who mmediately responded on social media in his preferred fashion -- launching a barrage of tweets attacking Kasich.

The U.S. needs to “intensify and broaden” its effort against Islamic State militants in Syria and Iraq, including sending more ground forces, Hillary Clinton said Thursday in a speech that set out clear differences with the Obama administration as well as the Republican presidential field.

“A more effective air campaign is necessary, but not sufficient,” Clinton said. “We should be honest that to be successful, airstrikes will have to be combined with ground forces” to take back the territory that Islamic State, also known as ISIS or ISIL, has conquered in Syria and Iraq.

Clinton's speech laid out a significantly more active approach toward combating Islamic State than President Obama has been willing to accept, a view she shied away from last weekend during the latest Democratic candidates' debate.

Clinton, the former secretary of State, repeated her call for creating “no-fly” zones in northern Syria, which Obama has rejected; sharply criticized Turkey and Saudi Arabia, U.S. allies that have been on-again, off-again partners in the effort against Islamic State; and said the U.S. should make clear to the Iraqi government that Washington will arm Sunni Arab militias and Kurdish forces in Iraq with or without Baghdad's cooperation.

She also warned that the encryption technology firms such as Apple have embraced for mobile phones and other devices may be interfering with the government's ability to prevent terrorist attacks.

“We need Silicon Valley not to view government as its adversary,” she said, but to work with the government “to develop solutions that will both keep us safe and protect our privacy.”

In the aftermath of last week's attacks in Paris, which French authorities say were planned by Islamic State, the question of how to combat the group has become central to the presidential campaign.