A super PAC that made a big splash by helping take down a few House incumbents this primary season has scaled back its involvement in recent weeks thanks to a cash shortfall.

Rep. Charlie Rangel (D-N.Y.) speaks about the New York Police Department's stop and frisk policy earlier this month. (AP Photo/Haraz N. Ghanbari)

And with still nearly half of congressional primaries to come — including some inviting targets in Tuesday’s primaries — it doesn’t appear the super PAC will be able to take advantage of some solid opportunities to unseat other incumbents in the weeks ahead.

A few incumbents face legitimate primary challenges on Tuesday, including Sen. Orrin Hatch (R-Utah) and Reps. Charlie Rangel (D-N.Y.), Nydia Velazquez (D-N.Y.) and Doug Lamborn (R-Colo.). But so far, the super PAC has only gotten behind a challenge to Rangel.

And while it spent upwards of $200,000 in more than a dozen primaries early this year, it has spent just $4,000 so far against Rangel with less than a week to go.

“It’s a real opportunity; I just don’t know if we’re going to be able to afford it,” the super PAC’s biggest benefactor, Leo Linbeck, told the Post’s Paul Kane in an interview at his home in Houston last month. “We’re working real hard to raise enough money to be able to make an impact.

“If you don’t have the cash, you can’t play the game.”

The super PAC has spent the money to significant effect, playing a significant role in unseating Reps. Jean Schmidt (R-Ohio), Don Manzullo (R-Ill.), Tim Holden (D-Pa.) and Silvestre Reyes (D-Texas) in their primaries. (Here’s a handy recap of the races it has played in, courtesy of Daily Kos Elections.)

But it has gradually spent less and less on primaries. Previously, it targeted a pair of incumbents in states like Alabama, Illinois, Ohio and Texas. This month, despite 14 states holding primaries, it has only spent money against Rangel.

(It also has $390,000 in debt, owed to Linbeck. But that money doesn’t necessarily need to be repaid.)

Campaign for Primary Accountability spokesman Curtis Ellis said the committee is plenty active in the Rangel race through its 501(c)(4) non-profit arm, the Alliance for Self Governance, which can’t specifically advocate for or against a candidate but can focus on turning out voters.

He said the group also has started eyeing its 2014 effort, hoping to bring forward more quality primary challengers deserving of the super PAC’s support.

“We’ve demonstrated that our concept works,” Ellis said. “We are looking and focusing on the longer term in 2014. What we saw here in this cycle was a dearth of credible primary challengers. And we hope and want to encourage more challengers in the 2014 cycle.”

As of now, though, even as some credible challengers step forward against candidates like Lamborn and Velazquez, the super PAC doesn’t have the funds to really get involved.

Linbeck also indicated that he wouldn’t be able to fully fund the operation going forward, and that others would need to step forward. Linbeck has given the super PAC $1.3 million to date. Other top donors include businessman Joe Ricketts , who gave $500,000 to the super PAC last year.

“I’m not a gazillionaire,”Linbeck said. “I’m contributing at a painful level. It’s just going to take more people.”

Paul Kane contributed to this report.