Updated

“I hear Pittsburgh is very nice this time of year.”

-- A senior Romney campaign staffer talking to Power Play about the strategy for the closing weeks of the campaign.

Two weeks ago, Mitt Romney trailed in five Rust Belt battleground states by an average of 6.9 points in the Real Clear Politics Average of polls. This morning, his average deficit was just 3.2 points.

While all 11 swing states have moved his direction since the Republican nominee’s boffo performance in his first debate with President Obama, Romney has seen the most significant improvement in the core column of the swing states: Pennsylvania, Ohio, Michigan, Wisconsin and Iowa.

Power Play readers have long known that the 2012 election would come down to the nation’s industrial heartland. Yes, Florida, Virginia and North Carolina are crucial for Romney. And certainly the president needs to hold on to his Western firewall in Colorado, Nevada and New Mexico.

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But this election, like most in recent memory, was always going to be about how those folks in the I-70 corridor and surrounding areas would vote. With 70 electoral votes up for grabs – votes that Obama swept in 2008 – the battleground stretching between Allentown, Pa. and Sioux City, Iowa has been the main front in this political war.

This has been increasingly Democratic territory for 20 years. In five elections, only Ohio and Iowa have voted Republican at all. In 25 contests in that time, the GOP has triumphed just thrice, Ohio in 2000 and 2004 and Iowa in 2004.

Long ago, this was the Republican Party’s stronghold. But as the economy declined over the last 40 years and the nation’s economic engine shifted to the South, the Red Team has found a less receptive audience in the Rust Belt for a message of reduced government assistance and free markets.

It’s been this trend that has presented the greatest danger to Republicans.

Democrats have long been a costal party, racking up easy wins in electorally rich Northeastern and Pacific Coast states. So for Republicans to win national elections they have to sew together their southern states and the Rust Belt.

The open question going into 2012 was whether Romney could prevail in these blue-collar states. Certainly the president’s strategy of focusing on Romney’s great wealth and his record as a CEO were intended to tell the white, working-class voters with whom the president has such problems that while they might not like the incumbent, the challenger is unacceptable.

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Republicans saw some of their greatest gains in 2010 in these five states, picking up 11 House seats two Senate seats. But Democrats assumed that Romney, a second-generation CEO, would be unable to replicate the success.

Romney looked headed for disaster in the Rust Belt in the weeks leading up to the debate, with Obama eyeing another sweep for the region.

But the tide has now turned and given the way viewers scored the second presidential debate on the key issue for the region – economic revival – it would seem that Romney will have a chance to make the president play defense in these states once thought safe by Team Obama.

The reason is that while Romney may seem less menacing to lower-middle class voters after seeing him in person, the president seems to be struggling with the electorate on the other side of the $50,000 median income line.

Obama can largely credit his 2008 success in the region to scoring well with suburbanites around Philadelphia, Pittsburgh, Cleveland, Columbus, Cincinnati, Milwaukee and Des Moines. These voters are generally more fiscally conservative than the Democratic Party and more socially liberal then the Republican Party, making Obama’s bipartisan, moderate message of four years ago a perfect sales pitch.

Dissatisfaction with Obama’s more liberal policies in office opened these voters to the idea of making a change. The president has been hammering Romney as an extremist on social issues, but it is hard for Obama to paint the Republican nominee as a hardliner after many months in which members of his own party decried Romney as too moderate.

Plus, Romney’s corporate image may be bad news in Youngstown, but it does him good in the leafy subdivisions north of Columbus.

For Romney, winning Ohio is a must. But Obama can ill afford to give up any of the other four states. While both candidates will be blitzing make-or-break Ohio in the remaining 19 days, look for Romney to apply pressure on Obama in the other four states that make up the president’s firewall in the heartland.

Chris Stirewalt is digital politics editor for Fox News, and his POWER PLAY column appears Monday-Friday on FoxNews.com. Catch Chris Live online daily at 11:30amET  at  http:live.foxnews.com.