The conservative super-PAC Club for Growth Action raised nearly $391,800 during the month of December, according to new filings with the Federal Election Commission.

It was the super-PAC’s largest haul since September, and it mostly stemmed from known Tea Party donor Richard Uihlein, who wrote a $250,000 check to the sister organization of the powerful anti-tax group. Uihlein is the chief executive of Uline, a packing supply company.

Donations to the super-PAC suffered from peaks and valleys in 2013 during a non-election year, ranging from just more than $2,000 in March to $683,770 in September. But the super-PAC ended the year with $1.7 million in the bank.

In one of the group’s first declarations of the year, Club for Growth’s super-PAC recently ran an advertisement targeting Rep. Justin AmashJustin AmashTrump, GOP at new crossroads on deficit Rand Paul revels in role of Senate troublemaker GOP lawmaker hits Trump over Dem memo: Americans deserve to read both MORE’s (R-Mich.) Republican primary challenger, businessman Brian Ellis. 

Club for Growth Action only spent $150 in independent expenditures during December for “website maintenance,” according to forms.