(CNN) -- Facing fire from some fellow Democrats for his decision to endorse Sen. Barack Obama, Gov. Bill Richardson said Sunday he still considers himself loyal to the family that helped make his political career.
"I am very loyal to the Clintons. I served under President Clinton. But I served well. And I served the country well. And he gave me that opportunity," Richardson told "Fox News Sunday."
"But you know ... it shouldn't just be Bush, Clinton, Bush, Clinton," he said.
Richardson was secretary of energy under the Clinton administration, a post that helped bring him to national prominence and win the governorship of New Mexico in 2002.
Richardson, who abandoned his presidential bid January 10, endorsed Obama on Friday as the Democratic nominee. He called Sen. Hillary Clinton Thursday to tell her of his decision, Clinton's campaign said. Watch what was behind Richardson's decision »
The Clinton campaign shrugged off the endorsement. "Both candidates have many great endorsers, but the voters, not endorsers, will decide this election, and there are still millions of voters in upcoming contests who want to have their voices heard," Clinton spokesman Jay Carson said.
Richardson was asked Sunday about James Carville's comment that Richardson's Obama endorsement "came right around the anniversary of the day when Judas sold out for 30 pieces of silver." Carville is an adviser to Clinton's presidential campaign and a CNN political analyst.
"Well, I'm not going to get in the gutter like that," Richardson said. "And you know, that's typical of many of the people around Sen. Clinton. They think they have a sense of entitlement to the presidency."
Gov. Ed Rendell of Pennsylvania, a prominent Clinton supporter, told Fox that he has no problem with Richardson's decision. He accused the Obama campaign of complaining about negativity while launching unfair attacks on Clinton.
Discussing a spat over whether Bill Clinton had challenged Obama's patriotism, Rendell said Obama is trying "to have it both ways."
The former president's remark last week that "it would be a great thing if we had an election where you had two people who love this country" sparked a dispute over whether he was questioning Obama's patriotism.
The full quote: "I think it would be a great thing if we had an election year where you had two people who loved this country and were devoted to the interest of this country. And people could actually ask themselves who is right on these issues, instead of all this other stuff that always seems to intrude itself on our politics."
The Clinton campaign denied any slight to Obama's patriotism. But retired Gen. Tony McPeak, an Obama surrogate, compared Clinton to Joe McCarthy.
McCarthy was a senator who was known for leveling accusations that people were Communists or spying for the Russians in the 1950s.
Richardson said he does not think former President Clinton was implying that Obama is unpatriotic.
Richardson added, "The campaign has gotten too negative -- too many personal attacks, too much negativity that is not resounding with the public."
Rendell responded, "They say the campaign's too negative, and they go out and turn an innocent remark -- Bill Clinton was saying what a lot of us feel ... If they want to tone it down, don't accuse someone of McCarthyism."
Richardson responded, "There's been negativity on both sides."
Rendell also accused the Obama camp of contradicting itself in another way that Richardson's endorsement highlights.
"First, they say the superdelegates should reflect the will of the people of their states. Well, we have Sen. Kennedy and Sen. Kerry saying they're going to vote for Obama even though Sen. Clinton won by 13 points in Massachusetts. ... The voters of New Mexico chose Sen. Clinton. If we follow the Obama line, Bill Richardson should be for Sen. Clinton."
"Yes, but, Eddie, by half a percent -- come on," Richardson responded, in a reference to the slight margin by which Clinton won New Mexico.
In a February interview with The New York Times, Richardson discussed how superdelegates should vote. "It should reflect the vote of my state, it should represent the vote of my constituency," he told the newspaper at the time.
Speaking to the Fox news program Sunday, Richardson said he believes Obama, 46, represents "change" and "I feel that it's important that we bring a new generation of leadership." Watch how age plays into the Democratic race »
Before dropping out of the race, Richardson, 60 -- the same age as Clinton -- ran on his experience. His campaign called him "the only candidate with the foreign policy experience and vision to restore America's standing around the world." E-mail to a friend