She hasn't even announced her Senate candidacy yet, but New York Rep. Carolyn Maloney's likely challenge of Sen. Kristen Gillibrand in the state's Democratic primary already is stirring dissension among party leaders.

The White House has played an active role in clearing the primary field for Gillibrand, who was appointed by Gov. David Paterson earlier this year to fill the Senate seat vacated by Hillary Clinton when President Obama tapped Clinton to be his secretary of state.

But former President Bill Clinton is headlining a fundraiser for Maloney in what could be seen as a snub to the Obama White House. And New York Rep. Charles Rangel rebuked Obama for meddling into the primary as Rangel defended Maloney's right to run.

"I really don't understand why President Obama got involved in our primary," Rangel told the New York Daily News. "I don't want to use the word wrong, but it doesn't seem like the astute political thing to do."

Just days ago, Vice President Biden called Maloney to discuss the race, a sign that the White House didn't want a primary fight next year. Obama already has asked Rep. Steve Israel not to challenge Gillibrand, a request he honored. And White House Chief of Staff Rahm Emanuel told reporters last week that the White House would help Gillibrand's re-election bid.

Rangel said he hasn't yet decided who he will endorse, but he offered a glowing review of Maloney.

"I really cannot say anything negative about a senior member who wants to run and whose polls, at this point in time, appear to be in her favor," Rangel told the New York Daily News.

"Nobody can challenge that she's not a hardworking member of Congress," he said, citing her work on behalf of Sept. 11 victims and her landmark legislation protecting credit card holders. "She is certainly one of our most active members."

Maloney's record has won her the support of one prominent Democrat. Matt McKenna, a spokesman for Bill Clinton, said the former president will be attending a July 20 fundraiser in New York for the congresswoman.

McKenna disputed any suggestions that Clinton is taking sides in the race, saying Clinton's attendance at past or future fundraisers should not be perceived as an endorsement.

"We agreed to this event some time ago as a way of saying 'thank you' to Congresswoman Maloney for her efforts on his wife's behalf last year," McKenna said.

Bill Clinton also did a fundraising event for Gillibrand, but word of the Maloney event comes as the congresswoman moves toward formally announcing her candidacy. An adviser said this week she is running.

Both Maloney and Gillibrand supported Hillary Clinton's failed presidential bid, and Bill Clinton had made a point of thanking her supporters.

During the Democratic primaries last year, Bill Clinton publicly criticized Obama as untested and unready for the job of president. Hillary Clinton engaged in a grueling and ultimately losing battle with Obama for the party's nomination. Bill Clinton and Obama made amends and the former president campaigned for the Democratic nominee.

The Associated Press contributed to this report.