The investment, which will pay for a pair of TV ads, marks the first significant attempt by any outside group or rival campaign to target the front-running Republican presidential candidate. Months after writing Trump off as a gadfly, the conservative political establishment is now struggling over how to reverse his rise and his surprising durability atop the heap in polls.

The Club’s first spot implies Trump is more liberal than both of the leading Democratic candidates — former Secretary of State Hillary Clinton and independent Vermont Sen. Bernie Sanders — by noting he supports “higher taxes, national health care, and the Wall Street bailout.” After an 11-year-old clip from a CNN interview shows Trump declaring, “In many cases, I probably identify more as a Democrat,” a narrator declares the candidate is “really just playing us for chumps.”

The second ad focuses on Trump’s support for the Supreme Court’s 2005 Kelo decision, a rightwing bête noire that expanded the government’s ability to seize private property in the name of eminent domain.

The free-market group is using its super PAC, called Club for Growth Action, to finance the attack on the billionaire candidate. Trump, meanwhile, has largely been self-financing, though he hasn’t needed to spend to get his message out, since cable networks have been willing to devote wall-to-wall coverage to his campaign for the ratings bonanza he brings them. On Monday night, for example, both CNN and MSNBC dedicated near-continuous primetime air to a Trump rally in Dallas.

Club for Growth in recent cycles has irked more establishment Republicans by targeting some it described as insufficiently conservative in primaries. But its willingness to spend early against Trump could provide a roadmap to other groups eager to hobble him.