It was a signal of a new, tougher offensive as the crucial March 4 Texas and Ohio primaries near, the Washington Post said. Obama primary victories Tuesday in Wisconsin and Hawaii pushed the Illinois senator further ahead in the delegate count.

The two are scheduled to debate Thursday night in Austin as a prelude to the Texas primary.

"It is time to get real -- to get real about how we actually win this election and get real about the challenges facing America," Clinton, D-N.Y., told a cheering crowd at Hunter College in Manhattan Wednesday.

"One of us is ready to be commander in chief. Let's get real about this election, let's get real about our future, let's get real about what it is we can do together."

After 10 straight defeats, Clinton now trails Obama in overall delegates 1,351 to 1,262.