Liberal groups on Tuesday made it clear that they are not happy with news reports that the White House may be considering alternatives to a public plan in health care reform.

Rep. Raúl Grijalva (D-Ariz.), co-chairman of the 77-member Congressional Progressive Caucus, fired off a letter to President Barack Obama warning him against dropping a public insurance option from health care reform plans.

Grijalva described the “alarm and dismay— he felt after reading a Wall Street Journal story that cites White House Chief of Staff Rahm Emanuel offering support for a “trigger— mechanism, under which a public plan option is only part of health care if the marketplace fails to provide sufficient competition on its own.

“I want to be crystal clear that any such trigger for a strong public plan option is a non-starter with a majority of the Members of the Progressive Caucus,— Grijalva said.

“Moreover, I consider it unacceptable for any of the cost savings that you are negotiating with hospitals and other sectors of the health care industry to be made contingent upon a robust public plan option not being included in the final legislation,— Grijalva continued.

Obama sought to ease liberals’ concerns by issuing a statement that reaffirms his support for a public option. But many House liberals remain concerned that Emanuel is still pushing a deal for hospitals.

Those with lingering concerns include the liberal group MoveOn, which sent an e-mail urging its millions of members to call the White House to express their disappointment with Emanuel’s comments. The e-mail gives the phone number to the White House and asks members to report their call to a MoveOn Web site.

“Right now, when key committees are finalizing health care legislation, Emanuel’s remarks will only embolden conservative opponents of reform. He should be standing with the majority of Americans for a strong public health insurance option — not disastrous half-measures like the trigger,’— states the e-mail.