As a crowd of protesters shouted “kill the bill,” House Republicans on Thursday rallied opposition against the Democrats’ health care legislation, decrying the bill on the steps of Congress in a last-ditch bid to derail or at least delay the legislation heading toward a possible vote Saturday.

Thousands of protesters arrived by bus for the rally, which the GOP is calling an emergency “House Call.” The event drew the conservative “tea party” activists but unlike past rallies was officially sanctioned by House Republicans.

Republicans want those who attend to track down their elected representatives in Congress and put pressure on them to think twice about voting for the more than $1 trillion health care overhaul pushed by House Speaker Nancy Pelosi.

“They’re going to listen,” said Rep. Michele Bachmann, R-Minn., who originally called for the rally. “The biggest voice in the United States is your voice.”

Republicans are formally unveiling their version of a health care reform bill Thursday.