After an intense lobbying effort by the White House and Democratic leaders, the Senate Tuesday evening voted down an amendment offered by Sen. Byron Dorgan (D-N.D.) that could have blown a hole in the financing of the health care reform bill.

The measure, which under a Senate floor agreement needed 60 votes to prevail, was defeated 51 to 48.

Dorgan’s amendment would have allowed for the re-importation of prescription drugs, and could have scuttled a deal the pharmaceutical industry made with President Barack Obama and Senate Finance Chairman Max Baucus (D-Mont.) to lower prescription drug costs under health care reform.

The proposal sat on the floor for over a week while Democrats haggled internally with what to do. Ultimately, leadership chose to back an alternative amendment offered by Sen. Frank Lautenberg (N.J.). Both the Dorgan and Lautenberg proposals needed 60 votes to pass, and the latter failed as well, receiving 56 yes votes and 43 no votes.

With Republicans attempting to be spoilers by reversing their previous opposition to the proposal, 24 Senate Democrats who supported the bill last year voted to kill the amendment. Sixteen Republicans who had previously voted against the plan voted for it. Two GOP Senators — Jim Bunning (Ky.) and John Ensign (Nev.) — changed their votes from aye to nay when it became clear the amendment was not going to achieve 60 votes.

Dorgan steered clear of criticizing the president’s — and his own party’s — efforts to defeat the amendment in order to preserve the delicate compromise with the pharmaceutical industry, but he said some Senators had approached him in recent days to say they would oppose a policy they had previously supported.

“The last seven days we’ve seen a lot of votes stripped away,” Dorgan told reporters. “I believe seven days ago we had sufficient votes to pass it but I think what’s happened in the intervening period other things developed.”

He added, “It’s a great disappointment because it seems to me very hard to do health care reform without doing something about the escalating prices of prescription drugs.”