Virginia House Speaker William J. Howell (R-Stafford) on Thursday strongly defended a national conservative organization he used to lead, arguing that it has become a victim of intimidation and extortion.

Howell said the American Legislative Exchange Council, a group that has lost some of its corporate members in the past week, has been subjected to a six-month attack by liberal groups, including the Occupy movement, Moveon.org and billionaire George Soros.

In a testy exchange after a tense news conference, Howell blamed the advocacy group ProgressVA for issuing what he called an inaccurate report in January outlining ALEC’s legislative influence in Virginia. He also criticized The Washington Post for writing about the review. ALEC has ghostwritten legislation across the nation, including in Virginia.

Howell grew frustrated after a line of questioning from Anna Scholl, the executive director of ProgressVA, and after she asked him for clarification, Howell replied: “I guess I’m not speaking in little enough words for you to understand.’’

Scholl retorted: “I’m a smart girl, actually. I went to the University of Virginia. I benefited from public education in Virginia. I think words with multiple syllables will be just fine for me.”

Virginia Democrats immediately released a video of the exchange, taped by a staffer, and called on Howell to apologize for his “belligerent and mean-spirited attack.” Howell’s office did not respond to requests for comment.

“After four months of outrageous Republican attacks on women’s rights, I guess I should not be surprised by Speaker Howell’s statement,” said Susan Platt, co-founder of the Farm Team, which supports female candidates for office in Virginia. “It is distressing, to say the least, that Howell has so wholeheartedly embraced this national trend of rhetoric against women. It is becoming pervasive.”

During the news conference on Thursday, Howell also chastised reporters for their coverage of the two-year, $85 billion state budget as well as former governor Timothy M. Kaine (D) for making unilateral decisions regarding a Metrorail project to Dulles International Airport. (Kaine negotiated an agreement on the project at the urging of several Republicans, including then-Sens. John Warner and George Allen and Rep. Frank Wolf.)

Howell, ALEC’s national chairman in 2009, appeared at a Capitol Square news conference with business leaders to tout a survey by ALEC that showed Virginia has been named one of the best states in which to do business.

ALEC touts itself as a pro-business, free-market organization, and its members include legislators and private companies. Corporate members pay fees, which give them a say on legislative issues. In recent weeks, several corporations have dropped their support of ALEC following scrutiny of “Stand Your Ground” laws after the death of 17-year-old Trayvon Martin in Florida. The group had lobbied for similar laws in other states.

Howell said the group had nothing to do with the Florida case and the legislation there came before ALEC’s involvement. He predicted that ALEC, which had 65 new corporate members last year, will easily survive the latest defections.

Howell said the tactics used to pressure companies who are ALEC members included calls for boycotts that go back to the days of the Rainbow Coalition, Rev. Jesse Jackson’s political organization. “They have been very, very open . . . that they want to destroy ALEC,’’ he said. “It’s discouraging, disappointing to see this intimidation, this extortion that’s going on against ALEC right now.’’

Howell said the attacks are the result of ALEC’s success in promoting the free market as opposed to a “government-controlled economy.”

“It’s a great exchange of ideas,’’ he said.

At least 115 current or former members of the Virginia General Assembly have ties to ALEC, either by sponsoring bills, attending conferences or paying membership dues, according to the ProgressVA study. The state has spent $232,000 during the past decade to send legislators, primarily members of the Republican-controlled House of Delegates, to ALEC conferences and meetings.

Howell said ProgressVa’s study was inaccurate because it excluded other organizations, such as the National Conference of State Legislatures, a group some Republicans accuse of leaning left. NCSL differs from ALEC in that only legislators and staffers are able to be members, and NCSL rarely writes model legislation.

Scholl introduced herself to Howell after the news conference and asked about the inaccuracies he had raised. After the exchange with Howell, Scholl declined to comment, except to say she would still like that information.

ProgressVA used data from a national report to identify more than 60 Virginia bills that ALEC helped author. Those bills included a piece of legislation calling for companies that hire illegal immigrants to be shut down, and another that would give businesses tax credits to fund private school tuition for needy students. Virtually all of the bills were introduced by Republicans.

The list of Virginia bills also includes one championed by Howell for several years that would have helped protect a Fortune 500 company, Philadelphia-based Crown Cork & Seal, from asbestos lawsuits. It was one of the few bills Howell publicly supported, and it died in a tight vote.

Seven bills that ALEC helped author passed in the General Assembly, including measures on education, taxes and health care, according to the study by ProgressVA. One of the resulting laws laid the groundwork for Virginia’s legal challenge of the federal health-care law passed in 2010.