Updated

Texas Sen. Ted Cruz is having a good week, which is exactly why backers of Marco Rubio may be looking to take him down.

The two Republican presidential hopefuls have both seen their stock in the campaign rise after strong debate performances. In Cruz's case, he emerged unscathed from a very public spat with President Barack Obama and seems to have an edge on Rubio in the early battleground state of Iowa, where he has tied GOP front-runner Donald Trump in recent polls.

Cruz's surge in the Hawkeye state has one deep-pocketed Rubio backer's nonprofit group shelling out $200,000 for an ad blasting the Texas lawmaker on national security.

American Encore, a 501(c)4 organization founded by political consultant and Koch brothers' protégé Sean Noble, doled out the cash to run an ad in the Des Moines area that accuses Cruz of voting to "weaken  national security" and tells him to stop "leading from behind."

Noble has said that that his group is not supporting Rubio, although he personally is. Instead, Noble said the idea behind the ads is to help nominate a Republican candidate who can win the White House next November.

"There is probably more than one in that regard," Noble told Politico. "We just don't think that Cruz is one of them."

The new ad, which takes exception with Cruz's support of the USA Freedom Act, which restricted the National Security Agency's bulk collection of phone metadata, mixes imagery from the aftermath of the Paris terror attacks with a bomb exploding on a city street while the voiceover claims that Cruz voted to "weaken America's ability to identify and hunt down terrorists."

Noble added that the ad stemmed from his experience during the 2012 presidential election, "when we had people who were not electable doing damage" to Mitt Romney, the GOP's eventual nominee.

"Newt Gingrich was part of the reason Mitt Romney lost the general election, and I don't want that to happen again," Noble said.

Cruz's campaign has played down the ad, saying that Washington insiders are fearful of him because of his strong poll numbers.

"Because Ted Cruz is surging in the polls, the Washington cartel is now so desperate they would openly abandon the Fourth Amendment that protects citizens from unconstitutional searches," Cruz spokesman Rick Tyler said in a statement to the Texas Tribune on Monday. "We have to wonder what other parts of the Constitution they would gut."

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