The gloves are coming off.
The super PAC supporting Republican presidential candidate Jeb Bush, which is sitting on the largest political war chest in American politics, is preparing to air one of its most aggressive television ads against GOP front-runner Donald Trump and Sens. Ted Cruz (R-Tex.) and Marco Rubio (R-Fla.).
The new ad from Right to Rise USA comes just hours after Trump called for a "total and complete shutdown" ban on Muslims entering the United States, and as new polling shows the two senators surging in early primary states where Bush hopes to compete.
Using footage of the Oval Office, an announcer asks, "When the attacks come here, the person behind this desk will have to protect your family. Will he be impulsive and reckless like Donald Trump? Will he have voted to dramatically weaken counter-terrorism surveillance like Ted Cruz? Will he have skipped crucial national security hearings and votes just to campaign, like Marco Rubio?"
"Jeb has the experience and knowledge to protect your family," the announcer ads.
The ad is reminiscent of the infamous "3 a.m." ad that Hillary Clinton's campaign aired during the 2008 Democratic presidential primary to raise questions about the experience and judgement of then-Sen. Barack Obama.
The new ad is set to air in the four states holding the earliest contests — Iowa, New Hampshire, South Carolina and Nevada.
Right to Rise USA, led by Republican strategist Mike Murphy, has raised more than $100 million this year, but fundraising is believed to have slowed considerably in recent months. Regardless, the group plans to use what is believed to still be the largest political bank account in the country to air TV and digital advertising on Bush's behalf.
The group initially planned to air positive, biographical TV ads about Bush, including a 15-minute mini-documentary, "The Jeb Story," that aired in New Hampshire last weekend. But Murphy never ruled out singling out specific rivals at some point.
By law, the super PAC and the Bush campaign cannot coordinate but both entities have shifted to a national security and leadership focus in recent weeks, believing that their candidate can eventually jump ahead amid questions of Trump's behavior and the experience of Cruz, Rubio and others.
The attack on Trump comes as Republican rivals pounced on his comments late Monday. Bush used Twitter to call Trump "unhinged."
Cruz, meanwhile, voted this year for the USA Freedom Act, legislation that limited the federal government's ability to collect and keep Americans' cell phone data. Rubio has been criticized for having a lax Senate voting record and for skipping hearings of the Senate foreign relations and intelligence committees.
Rubio has repeatedly defended his absence from the Senate by saying he is focused on winning the presidency in order to enact meaningful change and that he receives regular briefings on foreign affairs and intelligence matters even if he skips actual hearings.
Spokespeople for the Trump, Cruz and Rubio campaigns didn't immediately respond to requests for comment.