With just four days to go before the election, Barack Obama's presidential campaign started a renewed push on John McCain's home turf.

In response to polling numbers that showed the Democratic Illinois senator gaining ground in Arizona, Georgia and North Dakota, the Obama campaign started airing two new 30-second television commercials Oct. 31.

"We think things have tightened up in Arizona," Obama campaign manager David Plouffe said  in a conference call with reporters.

A Cronkite/Eight poll released earlier in the week showed McCain with just a 46-44 lead over Obama. Plouffe said internal data from the campaign suggested that the race could be close in McCain's home state, a traditional Republican stronghold. Bill Clinton won Arizona in his 1996 re-election bid, the first and only time a Democratic presidential candidate has won the state's electoral votes since Harry Truman in 1948.

On Oct. 29, the co-chairs of McCain's Arizona campaign questioned the veracity of the Cronkite/Eight poll, and expressed confidence that the Republican senator would win his home state. They pointed to other recent polls that have shown McCain leading Obama in Arizona by 5-, 7- and 9-point margins.

The McCain campaign and the Republican National Committee recently began running robo-calls in Arizona, criticizing the Democrat as inexperienced and soft on terrorism.

"Something," the 30-second spot running in Arizona, highlights Obama's endorsements from former Republican Secretary of State Colin Powell and investor Warren Buffet, and touts Obama as a leader who will bring America together.

The second ad, "Rearview Mirror," questions McCain's economic policies. The ad is airing in Georgia and North Dakota.