Two top Republicans on the president's high-profile deficit reduction commission — Sens. Tom Coburn of Oklahoma and Michael D. Crapo of Idaho — said Thursday they will support the blueprint rolled out this week by the panel's co-chairmen — edging the plan closer to garnering the support it needs to be forwarded to Congress.

"Our debt crisis is a threat to not just our way of life, but our national survival," the conservative lawmakers said in a joint statement a day ahead of the showdown vote on the plan's fate.

The announcement came about an hour after Rep. Paul D. Ryan, Wisconsin Republican and also a commission member, said he would oppose the plan because it falls far short of properly tackling health care costs and the problems he said were posed by President Obama's new health care overhaul plan...