WASHINGTON - Anything but jubilant, President Barack Obama awkwardly kept a promise Wednesday he made to ensure passage of historic health care legislation, pledging the administration would not allow federal funds to pay for elective abortions covered by private insurance.

Unlike Tuesday, when a beaming Obama signed the health care law in a nationally televised ceremony interrupted repeatedly by applause, the White House refused to permit coverage of the event. It occurred in the Oval Office in the presence of a small group of anti-abortion Democratic lawmakers who had extracted the commitment over the weekend. The president supports abortion rights.

The political maneuvering occurred as the FBI announced it was investigating threats received by about 10 Democratic lawmakers in recent days in apparent connection with the intensely controversial health care law.

"All threats and incidents directed against members of Congress are taken seriously and are being investigated," the bureau's Washington field office said in a statement.

Meanwhile, the Senate held a relentless series of votes stretching past midnight as Democrats drove toward final passage of a second health care bill. The measure was drafted to supplement the first by sweetening benefits for seniors with high prescription drug costs and for lower-to-middle income families who cannot afford the cost of insurance.

By shortly after midnight, Republicans had offered 22 consecutive amendments, and over the course of nearly seven hours Democrats had rejected every one. It was unclear how much longer the night's voting would last.

Lacking the votes to stop the bill, Senate Republican leader Mitch McConnell of Kentucky, vowed, "We'll continue to fight until this bill is repealed and replaced with commonsense ideas that solve our problems without dismantling the health care system we have and without burying the American dream under a mountain of debt."

That drew a swift rebuttal from Majority Leader Harry Reid, D-Nev., who said the legislation Obama signed on Tuesday was a "wonderful bill" that would help millions with inadequate coverage or none at all.

The follow-up bill before the Senate included a second triumph for the administration on domestic policy. It generally strips banks and other private insurers of their ability to originate loans to students, in favor of direct government lending.

The government's savings would raise the maximum amount needy students could receive in Pell Grants, and pump about $2.6 billion over a decade into historically black and Hispanic colleges. The changes would mean the loss of billions of dollars for student lending giant Sallie Mae as well as large financial institutions such as Citigroup, JPMorgan Chase and Bank of America.

The bill passed the House on Sunday and it appeared Reid had as many as 57 votes in hand for its approval, far more than needed. Among 59 Senate Democrats, only Sens. Blanche Lincoln of Arkansas and Ben Nelson of Nebraska announced in advance they would oppose it.

Far outnumbered, Senate Republicans sought votes on politically-charged proposals that, while potentially troublesome for Democrats, were doomed to defeat. The first, to roll back the bill's Medicare cuts, was jettisoned on a vote of 56-42; the second, to strip out special projects, by 54-43.

Sen. Tom Coburn, R-Okla., proposed an amendment barring federal expenditures for supplying Viagra and other erectile dysfunction drugs to sex offenders and cracking down on fraudulent health spending. Coburn said it would save $650 million a year, Sen. Max Baucus, D-Mont., called it "a crass political stunt," and Democrats turned it aside 57-42.

By 56-43, the Senate rejected an amendment by Sen. Charles Grassley, R-Iowa, to force Obama and others in the government to obtain insurance coverage through new purchasing exchanges the law will create in 2014, as members of Congress and some staff would. The White House said the move was unnecessary because the president would do so voluntarily, but it was unclear whether the day-old law permitted him to.

Taken together, the day's events amounted to mop-up actions by the White House and Senate Democrats, one day after Obama signed into law far-reaching changes in the nation's health care system that had eluded presidents and lawmakers for a century.

At its core, the new law would expand health care to 32 million who lack it while cracking down on the insurance industry and cutting federal deficits by an estimated $143 billion over a decade. Most of the bill's estimated $938 billion cost for coverage would pay for assistance to help families with annual incomes of up to $88,000 pay for insurance, although small businesses also would receive subsidies as in incentive to cover their employees.