First, an appeals court tossed out his challenge to the federal health-care law. Months later, the Virginia Supreme Court rejected an assertion by Attorney General Ken Cuccinelli II that the state’s flagship university had to turn over documents on global warming to his office.

And last week, a judge dismissed his lawsuit against a major New York City bank he claims defrauded state and local pension funds of $40 million.

That makes the third legal defeat for Cuccinelli (R) in the past six months — a highly public setback for the outspoken attorney general as he kicks off his gubernatorial campaign ahead of what is expected to be a contentious primary next year.

Critics charge that Cuccinelli has engaged in high-profile cases to garner attention, saying he should instead resign to run for governor as most of his predecessors have done.

“He’s using his office to promote himself,” said James Rich, a longtime Republican activist in Fauquier County who supports Cuccinelli’s gubernatorial opponent, Lt. Gov. Bill Bolling (R).

But Cuccinelli’s dismisses the criticism, saying that his office’s court challenges are based on the law and the state constitution — not politics.

“It should come as no surprise to anyone who has watched Mr. Cuccinelli’s career that he is more motivated by fighting for constitutional principles and the law than a nice-looking win-loss record in court,” Cuccinelli spokesman Brian Gottstein said. “Because of that, he is willing to take on the difficult fights that few others would — those cases which may not provide easy wins.”

The attorney general has won some well-known cases, including defending the state’s redistricting plan and the disputed role of the lieutenant governor in organizing the state Senate as well as others on electric rates and Medicaid fraud. But last week, Fairfax County Circuit Judge R. Terrence Ney dismissed Cuccinelli’s complaint that the Bank of New York Mellon Corp. defrauded pension funds in Virginia. Ney decided that state law does not allow the Cuccinelli action to go forward.

Cuccinelli’s office is considering appealing to the Virginia Supreme Court or amending the case in Fairfax Circuit Court. “It is important to remember that the court’s ruling does not absolve the bank of wrongdoing,” Gottstein said.

Bolling, a lower-octane Republican who often has been overshadowed by the active attorney general, declined to comment. However, Bolling’s profile has been elevated in recent months because he presides over an equally divided state Senate.

Some political observers say that whether Cuccinelli’s legal losses inflict political damage on his gubernatorial quest depends on whether Bolling decides to attack him on the cases. But Mark Rozell, a political scientist at George Mason University, predicts Cuccinelli will not likely be hurt by his string of legal losses because they buoy support with members of his base, who prefer that he be aggressive.

“From a political standpoint, I imagine he doesn’t feel that matters all that much whether he prevails,” he said. “He is a cause-orientated guy. He’s going to fight what he believes in.”

Gary C. Byler, a lawyer and longtime Republican activist from Virginia Beach who leads the party’s 2nd Congressional District committee, also said the cases Cuccinelli has chosen to fight resonate with the party faithful.

“It’s one of the reasons people love him,” he said.

In his action against Bank of New York Mellon, Cuccinelli sought $900 million in damages and penalties, claiming that bank currency traders skimmed profits of transactions conducted for six state and local public pension funds by falsely reporting the rate at which currency was exchanged.

“We are pleased that the Virginia court dismissed the entire case against us, vindicating our position that the claims were without merit,” Mellon spokesman Kevin Heine said. “This decision and the recent dismissal of similar whistleblower claims in California underscore our long-held belief that these cases will not withstand legal scrutiny.”

The lawsuit, filed under the Virginia Fraud Against Taxpayers Act, a 2002 statute designed to encourage whistleblowers to come forward, is one of the largest non-health-care cases brought anywhere in the nation, legal experts say.

According to Cuccinelli’s office, the bank earned $4.5 million a year to hold and protect Virginia’s pensions. It managed $55.1 billion in state and local government retirement funds.