After struggling for months to dent Senator Barack Obama’s candidacy, the campaign of Senator Hillary Rodham Clinton is now unleashing what one Clinton aide called a “kitchen sink” fusillade against Mr. Obama, pursuing five lines of attack since Saturday in hopes of stopping his political momentum.

The effort underscores not only Mrs. Clinton’s recognition that the next round of primaries  in Ohio and Texas on March 4  are must-win contests for her. It also reflects her advisers’ belief that they can persuade many undecided voters to embrace her at the last minute by finally drawing sharply worded, attention-grabbing contrasts with Mr. Obama.

After denouncing Mr. Obama over the weekend for an anti-Clinton flier about the Nafta trade treaty, and then sarcastically portraying his message of hope Sunday as naïve, Mrs. Clinton delivered a blistering speech on Monday that compared Mr. Obama’s lack of foreign policy experience to that of the candidate George W. Bush.

“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 in a speech on foreign policy at George Washington University. “We can’t let that happen again.”