WASHINGTON (AP) – Barack Obama challenged Bill Clinton’s truthfulness Monday in a deepening feud with the husband of Obama’s Democratic presidential rival.

Obama’s rebuke of the former president, who is still extremely popular with Democrats, came on the holiday honoring Martin Luther King Jr., when both Bill and Hillary Rodham Clinton focused on the civil rights leader.

In an interview on ABC, Obama twice questioned Bill Clinton’s veracity.

“I have to say just broadly, you know, the former president, who I think all of us have a lot of regard for, has taken his advocacy on behalf of his wife to a level that I think is pretty troubling. You know, he continues to make statements that aren’t supported by the facts, whether it’s about my record of opposition to the war in Iraq, or our approach to organizing in Las Vegas,” Obama said on “Good Morning America.”

“You know, this has become a habit,” he said. “And one of the things that I think we’re going to have to do is to directly confront Bill Clinton when he’s not making statements that are factually accurate.”

The former president has accused Obama of exaggerating his anti-war record and handing out undeserved praise to Republicans. Clinton said he personally witnessed Obama’s union forces intimidating Nevada caucus voters and said an Obama radio ad suggested how Democrats could keep votes from his wife.

During an event honoring King in his hometown, Atlanta Mayor Shirley Franklin, an Obama backer, made a not-so-subtle pitch for Obama at historic Ebenezer Baptist Church — right in front of the former president.

“We are at the cusp of turning the impossible into reality,” Franklin said. “Yes, this is reality, not a fantasy, or a fairy tale.”

While the largely black crowd erupted in applause, Bill Clinton sat with his hands clasped in front of him. He has been criticized in the black community for casting aspects of Obama’s candidacy as “a fairy tale.”

When Clinton spoke, he toned down his remarks about the campaign and never mentioned Obama by name when saying Democrats had “bad choices” in the party’s nomination race.

In an interview that aired Monday on NBC’s “Today” show, Bill Clinton agreed that King would be excited about Obama’s candidacy.

“A great speaker, a smart man, someone who loves our country,” the former president said of the Illinois senator.

Clinton said he and his daughter, Chelsea, witnessed voter intimidation in Nevada, prior to the caucuses that his wife won on Saturday. He said a representation of the Culinary Workers Union, which endorsed Obama, was “following along behind us going up to everybody … saying, ‘If you’re not gonna vote for our guy we’re gonna give you a schedule tomorrow so you can’t be there.'”

The union denied engaging in any intimidation. The Las Vegas Sun concluded it depended on who was talking. Its column, by Michael Mishak, said Clinton’s campaign and her supporters claim the union intimidated a member into caucusing for Obama while the member herself called the incident more of a misunderstanding.

Bill Clinton has criticized an Obama radio spot, saying: “There’s a radio ad up in the northern part of Nevada telling Republicans that they ought to just register as Democrats for a day so they can beat Hillary and go out and be Republicans next week and vote in the primary. Doesn’t sound like the new politics to me.”

Obama’s ad did say Nevada independents and Republicans could switch their registration, but it did not mention Hillary Clinton.

The former president also criticized Obama for his comments about Republicans. He contended that Obama said that “since 1992, the Republicans have had all the good ideas. … I can’t imagine any Democrat seeking the presidency would say they were the party of new ideas for the last 15 years.”

Obama did praise Republicans, but he criticized them in the same comment: “I think it’s fair to say the Republicans were the party of ideas for a pretty long chunk of time there over the last 10, 15 years, in the sense that they were challenging conventional wisdom. Now, you’ve heard it all before.

You look at the economic policies when they’re being debated among the presidential candidates and it’s all tax cuts. Well, you know, we’ve done that, we tried it. That’s not really going to solve our energy problems, for example. So, some of it’s the times.”