The convention speeches have been made, the vice presidential nominees announced and the stage has been set for what could prove to be one of the most unpredictable presidential elections in recent history.

When the smoke clears, could this be the year Republicans, led by Donald Trump, finally retake Pennsylvania and its 20 electoral votes?

In most years, that would be a tall order. Pennsylvania has thwarted Republican ambitions in every presidential election since 1988, in large part because the Democrats start the race with a sizable registration edge, currently 918,000 voters.

But this year, Trump's unconventional campaign has broken nearly every political rule. The Trump campaign says it plans to invest heavily in Pennsylvania, and experts are beginning to see Pennsylvania as an attainable, and potentially a must-win, state for Trump. Even former Democratic Gov. Ed Rendell has said his party should not take the state for granted.

"They know we're in play," Rendell said. "Anybody who thinks we're not in play is crazy."

Trump has ground to make up. The most recent poll of Pennsylvania voters, conducted July 24-27 by Suffolk University in Boston, gave Hillary Clinton a 9-percentage-point lead among likely voters.

Here's how Trump could close the gap: Win over more voters in Republican-trending western Pennsylvania while chipping away at Clinton's advantage in heavily Democratic Philadelphia and its suburbs, which have been trending Democratic.

Pennsylvania has a plentiful supply of non-college-educated white male voters, a group that, at least nationally, has gravitated to Trump's message on issues such as trade, immigration and law-and-order.

About 31 percent of white men in Pennsylvania have college degrees, according to the Census Bureau's 2014 American Community Survey, ranking the state 29 out of 51 states and the District of Columbia. The state's population is 78.5 percent white, ranking it 19th, and more than two-thirds (67.2 percent) of its counties are at least 90 percent white.

"He seems to do well with those voters," said Geoffrey Skelley of the University of Virginia's Center for Politics. "There are a lot of those voters in the western part of the state, and we have seen that part of the state trending Republican."

Because of that, the center's nationally known Sabato's Crystal Ball election projection newsletter moved Pennsylvania from "likely Democrat" to "leaning Democrat," a category that includes states such as North Carolina, Iowa, Florida and Ohio that have more recently voted for Republican presidential candidates.

The FiveThirtyEight political website model, known for its accuracy, gives Trump an almost even chance of winning Pennsylvania.

On the other side of the state, Trump may not be as appealing. The Philadelphia suburbs are full of political moderates, especially college-educated women with whom Trump hasn't fared well.

"Where Clinton is going to pile up the votes is in Philadelphia and southeastern Pennsylvania," Philadelphia-based Democratic political consultant Larry Ceisler said.

Those suburbs could be key. In 2012, Republican Mitt Romney lost the Philadelphia suburbs by 123,327 votes to President Barack Obama on his way to losing Pennsylvania by 309,840 votes. But Trump isn't the same kind of candidate as Romney, noted Charlie Gerow, a Harrisburg-based Republican political consultant.

"I believe that Trump is very capable of out-performing Mitt Romney in the Philadelphia suburbs," he said, adding that Trump did well there in the primary.

The southeast corner of the state plays an outsized role in Pennsylvania elections. More than 1 in 3 Pennsylvania voters live in Philadelphia, its suburbs and the Lehigh Valley. And if Clinton wins those voters by a wide margin, as Democrats predict, Trump's popularity elsewhere in the state might not matter.

"There's not enough raw votes to overcome what she's going to walk out of this part of the state with," David Plouffe, former campaign manager and senior adviser to Obama, told reporters in Philadelphia last week.

Obama's 2012 margin of victory came primarily from four populous counties — Allegheny, Philadelphia, Delaware and Montgomery — where he piled up an insurmountable lead of 703,901 votes.

Joshua Lott / Getty Images The most recent poll of Pennsylvania voters, conducted between July 24 and July 27 by Suffolk University in Boston, gave Hillary Clinton a nine-point lead among likely voters. Experts say Donald Trump could close the gap in Pennsylvania by winning over more voters in Republican-trending western Pennsylvania while chipping away at Clinton’s advantage in heavily Democratic Philadelphia and its suburbs, which have been trending Democratic. The most recent poll of Pennsylvania voters, conducted between July 24 and July 27 by Suffolk University in Boston, gave Hillary Clinton a nine-point lead among likely voters. Experts say Donald Trump could close the gap in Pennsylvania by winning over more voters in Republican-trending western Pennsylvania while chipping away at Clinton’s advantage in heavily Democratic Philadelphia and its suburbs, which have been trending Democratic. (Joshua Lott / Getty Images)

Trump's shot at success relies on cutting into the margins in those counties, where he would benefit from low turnout in Philadelphia.

David Urban, the campaign's senior adviser for Pennsylvania, said Trump's following isn't monolithic or limited to blue-collar whites.

"I believe we have as many white-collar supporters as we have blue-collar supporters, as many in office buildings as drive trucks," he said.

The Trump campaign will battle for votes in Philadelphia and the suburbs, he said.

It will get help there from the state and national parties, said Bob Bozzuto, executive director of the Pennsylvania Republican Party.

The RNC and state party expect to lead the organizing and volunteer efforts, Bozzuto said, relying on existing networks of county-level GOP activists, and reaching out to attendees of Trump events, using lists of registrants provided by the Trump campaign.

So far, Trump's campaign has two staffers in Pennsylvania: Urban, an influential GOP lobbyist and former chief of staff for Sen. Arlen Specter; and state Chairman Ted Christian, who ran Arizona Sen. John McCain's 2008 campaign in Pennsylvania.

But it is hiring staff and will have the resources it needs to direct an enthusiastic band of Trump supporters, Urban said.

"I liken this to directing a firehose," Urban said. "The Trump supporters, we are really proud to have them on our side. They are going out and knocking on doors and dragging their neighbors out."

Clinton's supporters don't seem as fired up, he said.

Clinton's campaign already is entrenched in Pennsylvania. There are 300 organizers in 30 offices registering voters and building up state efforts, Clinton campaign Chairman John Podesta told Pennsylvania's convention delegates last week. He also touted coordinated efforts with U.S. Senate candidate Katie McGinty and other Democrats on the ballot.

"I believe at the end of the day, if it comes down to being a close race, our organizing program will pull us over the top," Clinton's director of state campaigns and political engagement, Marlon Marshall, told reporters last week.

With Tim Kaine as Clinton's vice presidential nominee, some statistical models put Virginia in Clinton's column and suggest states such as Colorado and Nevada, which are younger and growing more diverse, may also be leaning in her direction. That makes Pennsylvania key to Trump's electoral vote strategy.