A super-PAC that has led the way in the anti-Donald Trump efforts raised $4 million in February.
According to its filings with the FEC, Club for Growth Action received $2.5 million from investor brothers Warren and Jackson Stephens.
The conservative group launched an ad this week attacking Trump for his past support for single-payer healthcare. It has spent millions around the country campaigning against Trump. FEC filings show it spent $4.7 million last month, half of it on anti-Trump ads.
The raise is a big boost for the group, which reported less thatn $1 million raised in January.
The business mogul has repeatedly attacked the group, often noting that they have solicited large donations from him.