[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2009/images/10/19/art.hoffman.gi.jpg caption="The group, which is backing third-party candidate Doug Hoffman, calls Republican Dede Scozzafava and Democrat Bill Owens 'two liberals'."]
WASHINGTON (CNN) -The conservative Club for Growth is spending another $300,000 on a new ad attacking the Democratic and Republican candidates in the race to fill the congressional seat vacated by New York Rep. John Hughes.
The group, which is backing third-party candidate Doug Hoffman, calls Republican Dede Scozzafava and Democrat Bill Owens "two liberals" in a new television spot set to hit airwaves in parts of New York's 23rd district on Tuesday.
"Tired of choosing between two liberals for Congress?" a narrator asks in the ad, before calling Hoffman a "conservative Republican" and the "common sense choice."
The group has now spent more than half a million dollars in less than a month on ads that attack both Scozzafava and Owens.
The special election to fill McHugh's seat will be held November 3.