House Majority Whip Steve Scalise on Tuesday responded to criticism over a speech he gave more than a decade ago to a white supremacist group, acknowledging he made a "mistake" -- while ripping those using the incident "for political gain."

The No. 3 House Republican issued a brief statement Tuesday afternoon explaining the incident, which was first reported by a local blogger.

House Speaker John Boehner also issued a statement in support of Scalise, whom Democrats have hammered over the 2002 speech.

Scalise, of Louisiana, said that at the time he was speaking to "many different" groups as a state representative trying to build support for legislation that would cut spending and stop tax hikes.

"One of the many groups that I spoke to regarding this critical legislation was a group whose views I wholeheartedly condemn. It was a mistake I regret, and I emphatically oppose the divisive racial and religious views groups like these hold," Scalise said.

He added: "I am very disappointed that anyone would try to infer otherwise for political gain. As a Catholic, these groups hold views that are vehemently opposed to my own personal faith, and I reject that kind of hateful bigotry."

The reports of the 2002 speech raised questions about his GOP leadership position and drew harsh criticism from Democrats earlier Tuesday.

Drew Hammill, spokesman for House Democratic Leader Nancy Pelosi, called the incident "deeply troubling for a top Republican leader in the House."

He also said "Speaker Boehner's silence on this matter is yet another example of his consistent failure to stand up to the most extreme elements of his party."

But shortly afterward, Boehner released his own statement backing Scalise in his current leadership post.

"More than a decade ago, Representative Scalise made an error in judgment, and he was right to acknowledge it was wrong and inappropriate," Boehner said. "Like many of my colleagues on both sides of the aisle, I know Steve to be a man of high integrity and good character. He has my full confidence as our Whip, and he will continue to do great and important work for all Americans."

The incident was first reported by liberal Louisiana blogger, Lamar White Jr., who claimed old Internet posts showed Scalise was a speaker at a conference 12 years ago for the European-American Unity and Rights Organization (EURO), founded by former Ku Klux Klan grand wizard David Duke.

Scalise, in an earlier interview with the New Orleans Times-Picayune, explained that at the time, he was speaking to groups about his opposition to a local tax plan. He said he couldn't remember speaking to EURO, but said, "I didn't know who all of these groups were and I detest any kind of hate group."

He added: "For anyone to suggest that I was involved with a group like that is insulting and ludicrous."

CenLamar.com, which first reported on the event, said Duke did not attend the 2002 conference, but EURO's national director "served as his surrogate."

In a written statement, Scalise aide Moira Bagley Smith earlier had confirmed that Scalise addressed the group as it gathered at a New Orleans-area hotel near the neighborhoods that both Scalise and Duke represented during separate stints as state lawmakers. Smith said in her statement that Scalise spoke only to rally support for conservative fiscal policies in Louisiana, not to endorse the mission and views of his audience.

"He has never been affiliated with the abhorrent group in question," the statement said.

The Democratic Party raised doubts about the congressman's suggestion that he didn't know the group's background.

"The group was named the 'European-American Unity and Rights Organization,' it was founded by David Duke, and he was invited by two of Duke's longtime associates. It doesn't get much more clear than that," Democratic National Committee spokesman Mo Elleithee said in a statement. "That weak attempt at an explanation doesn't pass the smell test and raises far more questions than it answers."

According to ABC News, Duke also confirmed that Scalise spoke at the 2002 event -- about tax policy.

Duke told ABC News many people in attendance were Scalise's constituents, and it's unclear whether he knew "that it was my meeting or not." Duke had been living abroad in recent years and eventually moved to Italy, but in late 2013 was ordered expelled from the country. He since returned to Louisiana.

Scalise ascended to the No. 3 House post earlier this year after House GOP Leader Eric Cantor lost his primary and resigned. Former Whip Kevin McCarthy moved into Cantor's slot, and Scalise replaced McCarthy.

On Tuesday, McCarthy issued a statement saying: "Congressman Scalise acknowledged he made a mistake and has condemned the views that organization espouses. I've known him as a friend for many years and I know that he does not share the beliefs of that organization."

The Associated Press contributed to this report.