President Barack Obama has irked close allies in Congress by declaring he has the right to ignore legislation on constitutional grounds after having criticized George W. Bush for doing the same.

Four senior House Democrats on Tuesday said they were "surprised" and "chagrined" by Obama's declaration in June that he doesn't have to comply with provisions in a war spending bill that puts conditions on aid provided to the World Bank and International Monetary Fund.

In a signing statement accompanying the $106 billion bill, Obama said he wouldn't allow the legislation to interfere with his authority as president to conduct foreign policy and negotiate with other governments.

Earlier in his six-month-old administration, Obama issued a similar statement regarding provisions in a $410 billion omnibus spending bill. He also included qualifying remarks when signing legislation that established commissions to govern public lands in New York, investigate the financial crisis and celebrate Ronald Reagan's birthday.

"During the previous administration, all of us were critical of (Bush's) assertion that he could pick and choose which aspects of congressional statutes he was required to enforce," the Democrats wrote in their letter to Obama. "We were therefore chagrined to see you appear to express a similar attitude."

The letter was signed by Reps. David Obey of Wisconsin, chairman of the House Appropriations Committee, and Barney Frank of Massachusetts, chairman of the House Financial Services Committee, as well as Reps. Nita Lowey and Gregory Meeks, both of New York, who chair subcommittees on those panels.

Obama needs Obey and Frank in particular to push through Congress key pieces of his agenda, including health care and financial oversight reform.

The White House said Tuesday the administration plans to implement the provisions of the bill and suggested that Obama's signing statement was aimed more at defending the president's executive powers than skirting the law.

"The president has also already made it clear that he will not ignore statutory obligations on the basis of policy disagreements and will reserve signing statements for legislation that raises clearly identified constitutional concerns," White House spokesman Ben LaBolt said in a statement.

Bush issued a record number of signing statements while in office as he sparred with Democrats on such big issues as the war in Iraq.

Democrats, including Obama, sharply criticized Bush as overstepping his bounds as president. In March, Obama ordered a review of Bush's guidelines for implementing legislation.

"There is no doubt that the practice of issuing such statements can be abused," Obama wrote in a memo to the heads of executive departments and agencies.

At the same time, however, Obama did not rule out issuing any signing statements, which have been used for centuries. Rather, he ordered his administration to work with Congress to inform lawmakers about concerns over legality before legislation ever reaches his desk. He also pledged to use caution and restraint when writing his own signing statements, and said he would rely on Justice Department guidance when doing so.

Two days after issuing the memo, Obama issued his first signing statement exerting executive power after receiving a $410 billion omnibus spending bill. He said the bill would "unduly interfere" with his authority by directing him how to proceed, or not to, in negotiations and discussions with international organizations and foreign governments.

Obey and the other House lawmakers said this week that Obama's signing statement on the war bill will make it tougher in the future to persuade other lawmakers to support the World Bank and IMF.

If Congress can't place conditions on the money, "it will make it virtually impossible to provide further allocations for these institutions," they wrote.