A senior Republican senator who sits on the two Senate committees dealing with health care legislation said Wednesday that he is stepping away from the negotiating table, citing concerns about the towering cost of the plans on the table and the lack of bipartisanship.

Sen. Orrin Hatch of Utah had been part of a bipartisan group of seven lawmakers trying to hash out a health care reform compromise, but he has been absent from the talks for more than a week. He sits on the Finance Committee, where the bill is stuck, and the Health, Education, Labor and Pensions Committee, which approved its version of the package last week. 

"I told (Finance Committee Chairman Sen. Max Baucus) it would probably be better if I didn't come," Hatch told reporters Wednesday. He cited concerns with the cost of the $1 trillion-plus bill, with an employer mandate for coverage which he said would hurt low-income individuals and with a possible expansion of Medicaid beyond what many cash-strapped states would be able to absorb. 

Hatch is vehemently opposed to a government-run health insurance plan, an option included in the House and Senate plans. His departure from discussions is just the latest sign that moderate and conservative negotiators are concerned their voices are not being heard in the push to strike a health care reform deal in the next couple weeks. 

In a written statement released Wednesday afternoon, Hatch again cited concerns about cost and said he had grown "increasingly concerned" that President Obama and his congressional allies have been "unwilling" to prevent a bipartisan package from being "gutted" on the floor of the Senate or in a conference committee with the House. 

He praised Baucus but said "it has become increasingly clear to me that Senator Baucus has not been given the flexibility necessary to construct a realistic health care reform bill that can achieve true bipartisan support." 

Hatch told reporters he decided to "stand aside" because he didn't want to "mislead anyone." 

He said he's worried that Democratic congressional leaders "really are trying to pass either the House bill or the HELP committee bill." 

Obama, who has made daily public pleas for Congress to pass legislation out of both chambers by the August recess, plans to hold a prime-time news conference Wednesday night. 

FOX News' Trish Turner contributed to this report.