Former Florida Gov. Jeb Bush on Wednesday endorsed Sen. John McCain, joining a long line of national Republicans to back McCain in his primary fight with former Rep. J.D. Hayworth.

In a written statement, Bush praised McCain as “a proven conservative leader committed to reducing taxes, fighting wasteful spending and keeping America safe.”

“We need John’s continued leadership in the United States Senate, and I am proud to support him,” Bush said.

Already in the McCain camp were 2008 vice presidential nominee Sarah Palin, former Massachusetts Gov. Mitt Romney, Virginia Gov. Bob McDonnell, Sen. Scott Brown (Mass.), Sen. Jon Kyl (Ariz.) and the rest of Arizona’s GOP Congressional delegation.

Hayworth, meanwhile, is seeking to run to McCain’s right as an insurgent conservative candidate.

The latest Hayworth radio ad, introduced into the rotation Wednesday, attacks “moderate” McCain for “voting with Washington for 28 years.”

Another ad, launched Tuesday, paints Hayworth as “a good Christian and a good neighbor.”

“Unlike some leaders who shy away from their faith, J.D. Hayworth embraces it,” the narrator says.

The biggest question mark for Hayworth remains his fundraising.

His campaign launched a “Million Dollar March” initiative to raise $1 million this month. As of press time, Hayworth’s Web site reported raising $154,000, 15 percent of that goal.

McCain had $5.1 million in cash on hand at the end of 2009.