By Larry Kane

PHILADELPHIA (CBS) — In the final days of the campaign for president, Pennsylvania’s 20 electoral votes are suddenly looming large.

The latest challenge to the Romney campaign came from New Hampshire, where a poll average shows Pres. Obama in the lead.

With polls showing a dead heat nationwide in the popular vote, both campaigns are focused on the electoral votes.

Obama leads in nine of the “swing” states, and the math now says that Pennsylvania could be a must-win for Romney, with Ohio and Wisconsin both real problems for him now.

So, Mitt Romney is making a Bucks County appearance on Sunday, and Repubican VP candidate Paul Ryan heads to Harrisburg tomorrow.

An extra $5 million is going into last-minute GOP ads. The Obama campaign is answering in kind.

Two months ago, at the GOP convention, Pennsylvania Republican leaders were urging an investment in their state.  Now, with time running out, the Romney campaign is finally looking to recapture some momentum here.

Also, expect a visit from Bill Clinton to Pennsylvania before the election.  The average lead in the polls for Pres. Obama is 4+ percent.