A new CNN Poll of Polls of likely voters in Pennsylvania indicates President Barack Obama with a 49%-40% lead over Republican nominee Mitt Romney.

The poll is an average of the three most recent non-partisan live operator surveys in the Keystone state. All three polls were conducted in the past two weeks, entirely after the end of the Republican and Democratic conventions.

The CNN Poll of Polls was compiled Monday. The surveys averaged in the poll are the Philadelphia Inquirer (Sept. 9-12); Muhlenberg College (Sept. 10-16) and Mercyhurst University (Sept. 12-20). The Poll of Polls does not have a sampling error. Recent partisan polls in Pennsylvania indicate a closer contest in the race for the state's 20 electoral votes.

George H.W. Bush's 1988 victory in the state was the last time a Republican carried Pennsylvania in a presidential election. But the state remained competitive in the resulting cycles, until four years ago, when then Sen. Obama eventually ended up carrying Pennsylvania by 10-points over Sen. John McCain. But two years ago, the GOP enjoyed a strong showing in the midterm elections, winning back the governor's office, a Senate seat and five House seats from the Democrats.

But this cycle, the state has seen little candidate traffic. The president's last visit to Pennsylvania was on July 6, with Vice President Joe Biden last campaigning in the state of his birth on September 2. Romney's last visit to the state was on July 17, with Romney's running mate, Rep. Paul Ryan, last stumping in the state on August 21. Romney's son Josh spent two days last week greeting voters in western Pennsylvania.

"Political junkies will keep an eye on the northeastern part of the state. President George W. Bush won that region in 2004, but with Scranton native Joe Biden on the Democratic ticket in 2008, Obama won northeastern Pennsylvania by nine points in 2008," says CNN Polling Director Keating Holland. Romney must win in the central and western parts of the state and do better than Sen. John McCain did in the northeast if he wants to offset the big Democratic advantages in Philadelphia and Pittsburgh."

Pennsylvania is rated as "Lean Obama" in CNN's Electoral Map.

"Ninety-six percent of Pennsylvania votes on election day," Romney campaign political director Rich Beeson told CNN. "It is going to be in play up until the end."

Ad spending in the race for the White House has been relatively modest in Pennsylvania this cycle. Since the unofficial start of the general election in early April, just over $16 million has been spent to run commercials on broadcast TV, according to data provided to its clients by Campaign Media Analysis Group (CMAG), which tracks campaign advertising.

While the Obama campaign has outspent the Romney campaign $4.1 million to $366,000, pro-Romney super PACs and other independent groups have picked up the slack. The Republican groups have shelled out around $9.4 million to run spots, compared to around $1.8 million by the Democratic groups.