WASHINGTON — Senator Clinton is seeking to reframe the debate over foreign policy, casting herself as a voice of moderation and maturity between a hawkish Senator McCain and a Democratic rival, Senator Obama, whom she characterized as untested and “rash.”

In a speech here this afternoon, Mrs. Clinton stepped up her attacks on Mr. Obama’s inexperience, comparing him to President Bush and saying the American people would not need to guess “whether I would need a foreign policy instruction manual to guide me through a crisis.”

The former first lady criticized the freshman Illinois senator for “wavering” between boasting of his willingness to meet with rogue leaders on one hand while on the other hand “advocating rash, unilateral military action” to strike at potential terrorist targets in Pakistan.

Mr. Obama has said he would meet with the presidents of Iran, Cuba, and North Korea, among others, “without preconditions,” a stance that Mrs. Clinton today suggested would “legitimize rogue regimes” and “weaken American prestige.”

“It may sound good, but it doesn’t meet the real-world test of foreign policy,” she said.

She mentioned Mr. Obama by name only near the end of her speech, but she implicitly linked him to Mr. Bush by warning against electing a president untested in foreign policy. “We’ve seen the tragic result of having a president who had neither the experience nor the wisdom to manage our foreign policy and safeguard our national security,” Mrs. Clinton said. “We can’t let that happen again. America has already taken that chance — one time too many.”

Citing her involvement in foreign policy as first lady and her years on the Senate Armed Services Committee, she said she was the candidate most ready to be commander in chief.

The Obama campaign released a statement after the speech by Major General J. Scott Gration, who said: “It’s ironic that Hillary Clinton compared Barack Obama to George Bush when she voted to authorize the war in Iraq, supports the Bush policy of not talking to leaders we don’t like, and gave George Bush the benefit of the doubt on Iran and Pakistan.”

Mrs. Clinton spoke in sober, measured tones for most of her 30-minute speech at George Washington University. The address offered no new proposals or prescriptions; instead she made a renewed case that she can break away from the foreign policy of the Bush administration while keeping a steady hand at the helm.

The rigors of a 14-month campaign appeared to catch up with Mrs. Clinton once again this afternoon, as she suffered a coughing fit and lost her voice about two-thirds of the way through her speech. “I talk way too much,” she said between coughs. Her voice didn’t reach above a whisper for several minutes, but she finished the address.

The Obama campaign had initially responded to Mrs. Clinton’s speech even before she delivered it, convening a conference call with reporters during which top foreign policy advisers questioned her judgment in voting to authorize the Iraq war and in supporting a Senate resolution last year that labeled the Iranian Revolutionary Guard as a terrorist organization.

“What is important on Day One is to get it right,” a senior Obama adviser, Susan Rice, said, referring to Mrs. Clinton’s oft-repeated refrain that she is “ready to lead on Day One.”

Ms. Rice said Mrs. Clinton’s vote denouncing the Revolutionary Guards made her “part of the neoconservative drumbeat for war with Iran.”

While Mrs. Clinton suggested Mr. Obama was unprepared for the presidency, she placed the likely Republican nominee, Mr. McCain, at another extreme. “Senator McCain can’t seem to budge from Bush approach that insists on using military force when diplomacy is needed,” Mrs. Clinton said.