Previewing his strategy leading into this week's GOP debate, former Florida Gov. Jeb Bush is contrasting his record against those of Republican governors running for president.

“Of all the governors on the main debate stage on Sept. 16, Jeb Bush is a clear-cut conservative reformer with the best record of results,� reads a full-page ad scheduled to appear in the New Hampshire Union Leader on Monday.

The hockey-themed ad calls Bush's record on taxes, spending and job creation “the Jeb Bush hat trick.� The ad compares Bush's record in the three areas with those of Wisconsin Gov. Scott Walker, former Arkansas Gov. Mike Huckabee, New Jersey Gov. Chris Christie and Ohio Gov. John Kasich.

Bush, who is slumping in the polls, has grown increasingly aggressive in confronting front-runner Donald Trump.

Bush's performance in the first debate, in Cleveland in August, was deemed lackluster by many political observers. Wednesday's debate at the Reagan Library in Simi Valley offers the candidate an opportunity to try to stand out in the crowded GOP field.

A CNN/ORC poll released Sunday finds that 43% of Republicans believe President Obama is Muslim.

The poll created a buzz on social media as Republicans enter an election year looking to win back the White House from Democrats.

Obama was born in Hawaii and is Christian, but since his election in 2008, some conservatives have continually questioned his faith and his citizenship.

Here are some details from the poll:

43% of Republicans believe Obama is Muslim, compared with 28% of Republicans who believe he is Christian.

Of Democrats, 15% believe Obama is Muslim, compared with 61% who believe he is Christian.

The poll surveyed 1,012 adults Sept. 4-8.

Vermont Sen. Bernie Sanders, among the most liberal of Democrats vying for the party's nomination, said Sunday he doesn't have a specific number in mind when it comes to how many Syrian refugees the United States should accept.

His comments come a week after a fellow Democratic challenger, former Maryland Gov. Martin O'Malley, said the U.S. should accept at least 65,000 refugees next year. O'Malley's call echoes that of the International Rescue Committee, which has said the current U.S. commitment to accept an estimated 8,000-10,000 refugees is just a first step.

"I think it's impossible to give a proper number until we understand the dimensions of the problem," Sanders said Sunday on NBC's "Meet the Press."

Sanders added, "People are leaving Iraq, they're leaving Syria, with just the clothes on their backs. The world has got to respond. The United States should be part of the response."

Democratic front-runner Hillary Rodham Clinton has said the U.S. must help refugees but also has been reluctant to offer a number as to how many refugees the country should accept. A majority of GOP White House hopefuls have offered similar assessments.

Many European nations, such as Germany, have committed to accepting as many as 800,000 refugees fleeing Syria's ongoing civil war.

Donald Trump, the persistent front-runner in the crowded field of Republican presidential hopefuls, sought to dampen the rising candidacy of Dr. Ben Carson on Sunday, questioning his ability as a leader.

In several national polls, along with those in early nominating states, Trump, a billionaire businessman, and Carson, a retired neurosurgeon, lead the pack of GOP presidential candidates and are both appealing to voters because of their outsider status.

From rival candidates to journalists, Trump has castigated anyone who has even slightly criticized his campaign -- leaving Carson as his most recent target.

"I'm a deal maker. I'll make great deals for this country," said Trump, speaking on CBS' "Face the Nation." "Ben can't do that. Ben's a doctor and he's not a deal maker and I'll make great deals for our country, which is very important."

In a USC Dornsife/Los Angeles Times poll released on Sunday, California Republicans widely favor a pair of outside candidates when it comes to the party's presidential nomination.

Billionaire businessman Donald Trump won the support of 24% of California Republicans surveyed, while Ben Carson, a retired neurosurgeon and lesser-known conservative favorite, was backed by 18%.

The poll comes ahead of Wednesday's Republican Presidential Library debate in Simi Valley.

Read more of Cathleen Decker's analysis of the poll.

Will the field of Republican presidential hopefuls offer an optimistic or pessimistic outlook for the country when they take the stage Wednesday at the Reagan Presidential Library?

As the 2016 election enters the fall, candidates have unveiled stark messaging strategies.

There's Donald Trump, who notes America is "in serious trouble." And Jeb Bush, who says the country is "on the verge of the greatest time to be alive in this world."

The Times' Mark Z. Barabak explores the different messaging put forth by the GOP field.