Grover Norquist, president of Americans for Tax Reform, on Thursday likened Republican lawmakers who vote for tax increases to "rats" whose actions ruin the GOP brand.
He argued the pledge had helped to brand "the modern Republican Party as the party that would not raise your taxes."
And to illustrate how important branding can be for a party, Norquist suggested that Republicans who are open to tax increases poison the GOP brand in much the same way a rat head found in a bottle of Coca-Cola would poison the Coke brand.
"Republican elected officials who vote for tax increases are rat heads in a Coke bottle," Norquist said, to loud cheers and applause from the crowd.
He went on to argue that while opposing tax increases is "step one" to limiting government, step two is to "stop spending so much of other peoples' money." He says the Tea Party has worked to make lower taxes and spending a mainstream focus of the Republican Party as a whole.
Norquist's comments came as an introduction to a panel he moderated Thursday afternoon on a balanced-budget amendment to the Constitution.