Obama talks tough on Pakistan

"At the same time, we recognize the sovereignty of the Pakistani government and realize that they're putting on a serious push ... They're taking the fight to al Qaeda," Snow said.

The Clinton campaign did not respond immediately for a request for comment on Obama's remarks. Another Democratic rival, Delaware Sen. Joe Biden, thanked him for a "Johnny-come-lately" position.

Obama unleashed a withering critique of President George W. Bush's foreign policy and said he would roll back Bush's warrantless eavesdropping program and close the U.S. military prison at Guantanamo Bay, Cuba.

A poll by The Wall Street Journal and NBC News said Clinton has widened her lead over Obama, going up to 43 percent in July from 39 percent in June. Obama tallied 22 percent, down from 25 percent in June.

Those polled cited Clinton's experience and competence highest among her positive attributes.

IRAQ AND AFGHANISTAN

Obama criticized Bush's emphasis on al Qaeda in Iraq and said as president he would end the war there and refocus efforts on the al Qaeda threat in Afghanistan and Pakistan by sending at least two additional U.S. brigades to Afghanistan.

He said that "because of a war in Iraq that should never have been authorized and should never have been waged, we are now less safe than we were before 9/11."

(Additional reporting by Missy Ryan)