Heritage Action on Wednesday said it opposes a military strike against Syria, a position that will put pressure on Republicans to block President Obama’s request.
The group said Tuesday’s Senate hearing made it clear there was no vital U.S. interest at stake.
Heritage Action’s opposition came as groups on the left also urged a no vote.
The liberal Progressive Change Campaign Committee released a memo on Wednesday saying it opposed intervention.
“In the last 72 hours, we surveyed PCCC members across the nation — in every state and congressional district,” the group said in the memo. “We've received over 57,000 responses so far, and a clear result: Your progressive base stands firmly against military action in Syria.”
Pressure from the right and the left will make it difficult to gain the 218 votes needed in the House to win approval for authorization.
Democratic and GOP leaders have expressed support, but it is unclear that will carry muster with rank-and-file members of both parties.
According to The Hill’s count, 38 House Republicans have said they’re against or leaning toward opposing U.S. action. Thirteen House Democrats have come out publicly against the action.
Heritage Action is the political arm for the influential Heritage Foundation, headed by former Sen. Jim DeMint (R-S.C.), and has clashed recently with House Republican leadership on high-profile issues like the farm bill.