With just four weeks left until Election Day, Sens. Barack Obama and John McCain are preparing to face off in Tuesday night's high-stakes presidential debate.

The debate comes amid stepped-up attacks from both sides.

Gov. Sarah Palin accused Obama of "palling around with terrorists who would target their own country," and Obama's campaign released an ad quoting editorials that called McCain "erratic" and "out of touch."

On Monday, the Obama campaign released an online documentary that criticizes McCain over his involvement in the "Keating Five" scandal of the 1980s. Fact check: Did McCain intervene on behalf of Charles Keating?

The back-and-forth this weekend could set the stage for a more heated event than the first presidential debate -- one that had few sharp exchanges as both candidates largely stuck to their talking points.

At a campaign event in Denver, Colorado, last week, a voter asked Mc Cain when he was going to "let the gloves come off and go after" Obama.

McCain's response: "How about Tuesday night?"