U.S. Democratic presidential candidate Hillary Clinton speaks during a town hall in Waterloo, Iowa, Dec. 9. (Mark Kauzlarich/Reuters)

— Hillary Clinton on Wednesday castigated Donald Trump for proposing a ban on Muslims entering the United States, part of a new push by the Democratic front-runner, the White House and their allies to make the controversial billionaire the intolerant face of the Republican Party.

“Instead of showing leadership, some of the candidates in this presidential campaign are resorting to really ugly, hateful rhetoric,” Clinton said. “Donald Trump, he does traffic in prejudice and paranoia. It’s not only shameful, it’s dangerous.

Supporters at a question-and-answer session with Clinton here booed at the mention of Trump’s name, and Clinton seemed to draw encouragement from the response. The election is about selecting a commander in chief, she reminded the audience, as she drew a clear comparison between her national security bona fides and Trump’s.

“When he says he wants to stop all Muslims from entering the United States, that runs counter to what I and others who have actually been in the Situation Room, making hard choices, know we have to do,” she said.

With seven weeks to go before the first-in-nation Iowa caucuses, Clinton and other Democrats are confronting the very real prospect that Trump — long dismissed as a sideshow — could win in Iowa and eventually become the general election nominee.

Republican presidential candidate Donald Trump waves to the crowd at a Pearl Harbor Day Rally at the U.S.S. Yorktown on Dec. 7 in Mt. Pleasant, S.C. (Sean Rayford/Getty Images)

Clinton in recent days has sharpened her attacks on Trump and accused him of playing into the hands of terrorist recruiters. While reveling in Trump as a foil — and lashing other Republicans to Trump positions that could hurt the party in the general election — she is also for the first time treating him as a political equal.

Clinton’s campaign rushed to produce stickers proclaiming “Love Trumps Hate” after Trump’s remarks Monday that Muslims should be excluded from the country because of the risk of terrorism. She sought to raise money and sign up volunteers Tuesday with a long “message to Muslims” that assured Muslim Americans that “it’s your country too.”

And on Wednesday her campaign invited supporters to play an online “Trump or Not Trump” quiz asking which candidate said what. “Even if you get every answer right, America still loses,” Clinton said in a Twitter message.

The campaign will not focus only on Trump, a senior Clinton aide said Wednesday, but is seeking to hold him up as emblematic of GOP views.

“While he is commanding most of the attention and his statements may be the most shocking and bombastic, they are of a piece with what the whole field is espousing,” said the aide, who requested anonymity to discuss the state of the race ahead of Iowa.

That message is being echoed by the White House and other Democratic leaders as they seek to hang Trump’s controversial anti-Muslim and anti-immigrant message around the necks of the entire Republican field. In doing so, Democrats are acknowledging Trump’s longevity at the top of the polls while preserving the options to use his views against another candidate if he ends up fading in the spring.

President Obama speaks during an address to the nation from the Oval Office of the White House on Sunday night. (Saul Loeb/AFP/Getty Images)

Trump is up by an average of 3.4 percentage points in Iowa over closest rival Sen. Ted Cruz (R-Texas) in the Real Clear Politics compilation of recent polls, although one survey put Cruz ahead this week. Clinton is ahead of rival Sen. Bernie Sanders (I-Vt.) by nearly 14 points in the same polling average.

At the White House, the decision to attack Trump came after President Obama had spent recent weeks decrying the rising anti-Muslim rhetoric in the Republican Party, saying it was contrary to American values and threatened to aid the Islamic State terrorist group’s propaganda campaign against the United States.

White House press secretary Josh Earnest on Tuesday lit into the billionaire real estate magnate as a “carnival barker” whose “vacuous sloganeering” has a “dustbin-of-history-like quality to it.”

Earnest even mocked Trump’s hair, calling it “fake” and, when questioned about the assertion by a reporter, adding that he has “a rather outrageous appearance.”

The strategy was a clear effort to isolate Trump and drive a wedge into the GOP, daring the Republican establishment and rest of the presidential field to denounce the front-runner or risk being tied to his offensive rhetoric. It represented a rare foray into 2016 politics for a White House that has so far attempted to remain largely above the fray in hopes of focusing on Obama’s policy agenda.

“Mr. Trump has been rather cynical in appealing to people’s fears and anxieties,” Earnest said.

Vice President Biden amplified the message, calling Trump’s message a “very, very dangerous brew” for the country and predicting Clinton would “win in a walk” if matched up against him in the general election.

“Is this just a guy doing ‘Celebrity Apprentice’ for himself?” Biden said in an interview with Bloomberg News. “Is this just a guy who’s an entertainer? It may have started there, but, I now think, now, he wants to be president. But I don’t think there’s much chance of that.”

Other Democrats are not counting Trump out, and are beginning to game out a general election strategy against him. Clinton hinted at that prospect in an interview Sunday on ABC’s “This Week.”

“Who can agree with anything he says that is, you know, subject to one second of fact checking?” Clinton said with exasperation. “Look, if he gets the nomination, I will be more than happy to campaign against him.”

She laughed off Trump’s frequently expressed opinion that she has “no strength, no stamina,” which many Clinton supporters view as a thinly disguised sexist attack.

During a Wednesday visit to Capitol Hill to mark the 150th anniversary of the 13th Amendment, which abolished slavery, Obama alluded obliquely to the anti-Muslim rhetoric from Trump and others.

“We betray the efforts of the past if we fail to push back against bigotry in all its forms,” Obama said, urging the nation “to rise above the cynicism; to rise above the fear; to hold fast to our values; to see ourselves in each other; to remember that our freedom is bound up with the freedom of others regardless of what they look like or where they come from or what their last name is.”

“Or,” he added with emphasis, “what faith they practice.”

To that last line, the president received a standing ovation from his audience at Emancipation Hall.

After being put on the defensive over Obama’s anti-terrorism policy in the wake of the recent Islamic State-linked attacks in Paris and San Bernardino, Calif., the White House has attempted to shift the political conversation and sees an opportunity to turn the spotlight back onto the GOP’s overheated rhetoric.

The administration has long sought to paint the Republican Party as intolerant to the growing and ascendant pool of voters that helped power Obama’s rise — including women, blacks, Hispanics and gays. In March 2013, Republican National Committee Chairman Reince Priebus delivered a report on the 2012 election concluding that the GOP risked “marginalizing itself” with its rigid ideology and alienation of minorities.

Unless the party changed course and broadened its appeal, Priebus wrote, “it will be increasingly difficult” to win presidential elections.

After Earnest’s sharp attacks on Trump on Tuesday, White House political director David Simas followed up with a series of Twitter messages taunting House Speaker Paul D. Ryan (R-Wis.), Senate Majority Leader Mitch McConnell (R-Ky.) and the GOP presidential candidates for failing to say outright that they will not support a Trump candidacy.

The intensity of Earnest’s attack was so pronounced Tuesday that a reporter asked whether it was a low blow to mock Trump’s hair as fake.

“That’s a hallmark of his campaign and his identity, though,” Earnest said.

“How do you know it’s fake?” another reporter asked.

“I’m happy to be fact-checked,” the spokesman said with a shrug.

Nakamura reported from Washington.