WASHINGTON (AP) -- Once thought to be solidly behind President Barack Obama, younger voters burdened by a bleak employment picture, high gas prices and student loan debt are being aggressively wooed by the Democrat and his likely Republican challenger, Mitt Romney.

In 2008, Obama had a 34-point advantage over Republican Sen. John McCain among voters under age 30. He won about two-thirds of the vote in that age group.

But a new Harvard poll suggests the president may face a harder sales job with younger voters this time around. That survey shows Obama leading Romney by 12 points among those ages 18-24. Among those in the 25-29 age group, Obama holds a 23-point advantage.

It's an opening Republicans hope to exploit by focusing on disillusionment with the candidate who promised "hope" and "change."