Super PACs supporting Cruz are releasing more ads. (AP Photo/Jae C. Hong)

A new super PAC supporting the presidential bid of Sen. Ted Cruz has released its first campaign ad, part of $4 million in spots it plans to run in Iowa and South Carolina to support the Texas Republican.

Stand for Truth,  a group formed in November by Hal Lambert, a former finance chair of the Texas Republican Party, released the ad Tuesday. Titled "threats," it knocks one of Cruz's rivals for the nomination, Sen. Marco Rubio (R-Fla.) and his support for a failed Senate bill that would have granted a pathway to citizenship for undocumented immigrants. The ad suggests the attempts at reform are imperiling national security, by flashing photos of the Islamic State and the radicalized San Bernardino, Calif., couple who killed 14 people and injured 21 last month.

"We are at war. Not just abroad, but here at home," the ad says.

Lambert, the Fort Worth money manager and Cruz ally who started the group, declined to comment on its plans.

Read: The brutal immigration ad Marco Rubio knew was coming is here

It comes as a constellation of pro-Cruz super PACs, Keep the Promise, released an ad assailing Rubio for his support of the bill, known as "Gang of Eight" for the number of senators who introduced it. The ad ties Rubio to President Obama, with a clip of the president calling for comprehensive immigration reform, Rubio stating he supports a pathway to citizenship and Sen. Chuck Schumer (D-N.Y.), stating the bill had Rubio's "fingerprints are all over that bill."

The ads come as the number of super PACs supporting Cruz - at least eight - are confusing wealthy donors.

Stand for Truth launched its website this week, with a scroll of three images, including one that features a law enforcement officer and dog silhouetted against a fence. "No amnesty for illegal aliens," it reads.

Read: Ted Cruz is running a well-organized campaign. His super PACs — not so much.

The website also has buttons donors can press to auto-fill a donation; they range from $1,000 to $25,000, and has a section where the amount can be manually filled in.

Matea Gold contributed reporting.