WASHINGTON  Congressional Republicans are finding much to dislike in Democratic health care proposals, illustrating the immense difficulty Democrats face in fashioning an overhaul that can attract enough Republican support to be portrayed as bipartisan.

Republicans’ primary objection is the Democrats’ push for a public health insurance plan that would serve as an alternative to private coverage. Republicans say such a plan would cause the private insurance market to unravel.

There is also the potential 10-year price tag of $1 trillion or more for the overhaul, coupled with the prospect of new taxes or fees to offset the cost. And Republicans see elements of the Democratic plans as government intrusion into personal health care decision making.

Representative John A. Boehner of Ohio, the House Republican leader, said he was unaware of any House Republican inclined to support the Democrats’ proposed legislation.