Opening long-awaited congressional hearings, a top Republican said Wednesday an investigation of Planned Parenthood was intended to protect taxpayers from the kind of "horrors" suggested by secretly recorded videos of group officials discussing the sale of tissue from aborted fetuses.

In a session highlighted by partisan clashes, Democrats said the investigation by the GOP-led House Judiciary Committee was just the latest in a decades-long effort to curtail abortion rights and was based on deceptively edited videos that show no evidence of wrongdoing by Planned Parenthood.

"The purpose is to smear Planned Parenthood," said Rep. Jerrold Nadler, D-N.Y. In a reference to infamous hearings of the 1950s that featured unfounded allegations that some federal officials were communists, Nadler added, "Sen. Joseph McCarthy would be proud of this committee today."

Two months ago, a small group of anti-abortion activists began releasing videos it furtively recorded. Republicans and conservatives say those videos show Planned Parenthood was illegally selling fetal tissue for profit and violating other federal prohibitions.

Planned Parenthood and its Democratic defenders say there is no evidence of wrongdoing.

Representatives from Planned Parenthood and the Center for Medical Progress, which made the videos, did not testify.

The committee chairman, Rep. Bob Goodlatte, dismissed Democratic claims of unfairness. Goodlatte, R-Va., said comments by the Democratic presidential front-runner, Hillary Rodham Clinton, that the videos were "disturbing" undermine assertions that the investigation is inappropriate.

Goodlatte said Planned Parenthood "is granted huge amounts of federal funds" and Congress must "do what we can to ensure federal taxpayers are not contributing to the sorts of horrors reflected in the undercover videos."

Planned Parenthood provides contraception, tests for sexually transmitted diseases and abortions in clinics across the country. It receives more than $500 million each year from federal and state governments, more than one-third of its overall $1.3 billion annual budget.

Numerous Republicans want to end federal payments to Planned Parenthood. Democrats have blocked a Senate effort to do that, and GOP leaders are hoping to head off conservatives demanding that Congress not fund federal agencies starting Oct. 1 unless Planned Parenthood's money is terminated -- a move that would cause a government shutdown.

In a closed meeting with House Republicans, Speaker John Boehner, R-Ohio, expressed support for tightening legal curbs on fetal tissue sales and for cutting off Planned Parenthood's money, said one Republican who described the private session on condition of anonymity.

Boehner said Planned Parenthood could continue fetal tissue sales even if its federal money was blocked, and he expressed concern that a shutdown would damage the anti-abortion cause, the Republican said.

Wednesday's hearing was called to examine the federal laws that address fetal tissue research. But debate quickly expanded to views on abortion, an issue that has sharply divided the two parties. Until the videos were released, it was not expected to surface as a prominent issue in next year's presidential and congressional elections.

At one point, Goodlatte described the tearing apart of a fetus during an abortion and asked witness Priscilla Smith, who directs Yale Law School's Program for the Study of Reproductive Justice, if she considered that humane. Smith defended the procedure when used on a fetus that was not viable.

"Your idea of humanity and mine are very different," Goodlatte said.

Melissa Ohden, who says she survived a 1977 attempt to abort her, told lawmakers that she would "never, ever forget" the videos showing one Planned Parenthood official, while dining, discussing abortions and fetal tissue donations.

Democrats were angered by what they said was the one-sidedness of the hearing and Republicans' attacks on Planned Parenthood.

"Surely, the Congress has better things to do than spend its time helping to undermine an organization that provides vital health services," said Rep. John Conyers Jr. of Michigan, the top Democrat on the committee.

James Bopp Jr., general counsel for National Right to Life, told the lawmakers that the videos show that Planned Parenthood "violates various federal laws," including the prohibition on profiting from the sale of fetal tissue.

One comment on the videos he cited came from Dr. Mary Gatter, a regional Planned Parenthood medical director in California. While talking with abortion opponents who posed as private tissue buyers, Gatter said, "In negotiations, the person who throws out the figure first is at a loss, right?"

But Yale's Smith said "there is simply no evidence in these misleadingly edited videos of a violation" of statutes." She said the conversations show on the videos were actually unsuccessful attempts by the Center for Medical Progress to "entrap" Planned Parenthood officials into illegally selling tissue for profit.

Before the hearing, Planned Parenthood distributed a report saying that nine other times since 2000, it has been targeted in a "fanatical crusade" by anti-abortion extremists who have released recordings after trying to entrap the organization into wrongful behavior, only to see the allegations discredited.