WASHINGTON - Conservative Democrats in the House are rebelling against their party leaders and trying to put the brakes on the push to pass a health care overhaul by August.

The fiscally conservative Blue Dog Coalition plans to present a letter to House Democratic leaders Thursday raising concerns about costs and other issues and asking for more time, members of the group tell The Associated Press.

Democratic Rep. Mike Ross of Arkansas says that if the Democrats' liberal legislative plan came to the floor as proposed, an "overwhelming majority" of his group would oppose it. The Blue Dogs claim 52 members so that could endanger the bill.

The move comes just as House Democratic leaders are trying to finalize the proposed legislation and unveil it Friday.