Senate Democrats will take up healthcare again today after a tough week.

Republican opposition is building after independent auditors estimated their initial efforts could cost more and cover fewer than initially hoped, reducing the chance of winning the bipartisan support that could ensure that any reforms will last.

Republican Sen. John McCain gave Reuters a grim prognosis last Friday and said the next few days will determine whether the effort succeeds or fails.

But Democratic Sen. Max Baucus still thinks he can get a bipartisan bill to President Obama by the end of the year.

Today, the Senate Health Committee, which is working on a bill that is likely to be less Republican-friendly than Baucus’s effort, will resume work on its bill at 3 p.m.

Folks at the White House have healthcare on the agenda today as well.

President Obama will sign a bill that establishes significantly tougher tobacco regulations in a Rose Garden ceremony.

And Health Secretary Kathleen Sebelius and two other White House officials appeared on ABC’s “Good Morning America” to rebut Republican claims that their plan will lead to greater bureaucracy and a reduced level of care.

photo: REUTERS/Jonathan Ernst (Obama apeaks tothe American Medical Association in Chicago, June 15)

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