A light rain drizzled down on Donald Trump supporters as they boarded a bus in a grocery store parking lot in York, Pa.

Near the back, George Flinn sat with his wife and said he was looking forward to the rally he was going to for Mike Pence, the running mate of the Republican candidate for the U.S. presidency.

Flinn joined the Republican party on his college campus in 1964. He's loyal but has been dissatisfied with the party's presidential candidates for a long time. Then Trump came along and Flinn got excited.

"I've been a conservative all my life," he said during the ride to the garbage recycling facility where the event was held a few weeks ago. "Finally, we've got somebody I can get behind."

George Flinn, a longtime Republican, says he is finally excited about his party's presidential candidate, Donald Trump. (Meagan Fitzpatrick/CBC)

At the rally, some people sported Trump's "Make America Great Again" hats. Joyce Haspert wore a T-shirt with "Deplorable" printed on it, a reference to what Democratic candidate Hillary Clinton called her rival's supporters.

"I'm a Trump fan true and true," said Haspert. The 58-year-old said she loves what he stands for, particularly his promise to stop illegal immigration. "They are terrorists," she said.

When Pence took to the makeshift stage in the middle of the plant, scents of garbage hanging in the air, he thanked the crowd for coming on a rainy day even though they would rather see Trump.

"I know I'm not the main event," he joked.

Voters in Pennsylvania have had multiple opportunities to see Pence and Trump — the main event — in recent weeks. Trump paid a visit there again last Friday, holding rallies in two towns in different corners of the state. On Saturday, he was in Gettysburg, the famous Civil War battle site.

Pockets of red in a blue state

The repeat visits to the Keystone state show just how hard the Republicans are trying to win it. That's because the mathematical path Trump has carved out to lead him to the White House passes through Pennsylvania.

Joyce Haspert, a voter from York, Pa., was at a Mike Pence rally on Sept. 29, 2016, and was proud to be wearing a shirt that used the term Hillary Clinton called Donald Trump's supporters. (Meagan Fitzpatrick/CBC)

The next president needs to win 270 electoral college votes and Trump is making a play for the state's 20 votes to get him there.

Even though Democrats have won the state in the last six elections, it is a battleground state this year. Pockets of it lean right, where Trump's campaign messages appear to be resonating, and he recognized early on that he could be competitive with Clinton there.

"Pennsylvania's demographics have given him hope that this is the type of state that he could flip from blue to red and get him to 270," said Christopher Borick, a political science professor at Muhlenberg College in Allentown, north of Philadelphia, and director of its Institute of Public Opinion.

The demographics Borick and other political analysts describe are the lower-educated, white, working class, older voters who can be found in many of the towns in between Pittsburgh and Philadelphia. Those kinds of demographics match up with the groups that support Trump with buckets of enthusiasm.

The crowd at a Mike Pence rally in York, Pa., listens attentively to his speech in a garbage recycling facility last month. (Meagan Fitzpatrick/CBC)

Many of the towns in Pennsylvania's rural areas used to have thriving steel, coal and manufacturing industries, but factories and mills closed down and residents now struggle to find work.

When Trump talks about reviving those industries, bringing jobs back, scrapping federal regulations and renegotiating trade deals including NAFTA, he's finding receptive ears in these places.

Key battleground

"He's touched into a lot of feelings that everyone is having," Richard Dipietro said as he waited for Pence to take the stage at the recycling plant. "I think he's talking very straight. He's not a politician, which is really good."

To win Pennsylvania, Trump will need voters like Dipietro to turn out in big numbers in small towns like York. That's because Trump is struggling in the all-important Philadelphia suburbs. Those counties are full of higher-educated, higher-income voters — and there are a lot of them. In the 2012 election, they accounted for about 1.2 million of the 5.7 million votes that were cast.

It will be difficult for any presidential candidate to win Pennsylvania without winning those areas. Philadelphia and Pittsburgh are also vote-rich and largely Democratic, so Clinton is expected to get a head start with those votes.

Borick said Trump is hoping his losses in the two big cities won't offset any gains he makes in the rest of the state.

"That's a big risk and right now the polling in the state says it's a risk that hasn't worked for him yet," said Borick.

President Barack Obama gestures as he arrives at a campaign event for Democratic presidential candidate Hillary Clinton, Sept. 13, 2016, in Philadelphia. (Matt Rourke/Associated Press)

If Trump loses the Philadelphia suburbs and turnout in the city is solid, Trump's route to winning the state relies on "exceptional turnout" elsewhere, according to Borick. "That map is really a reach for him."

Clinton is leading Trump in the polls and to maintain that gap on election day she is also counting on certain demographic groups to turn out for her.

Clinton needs solid turnout

G. Terry Madonna, a professor and pollster at Franklin and Marshall College in Lancaster, Pa., said Clinton is winning African-American voters, who make up 19 per cent of the state's population, but they aren't showing as much enthusiasm for her as they did for President Barack Obama.

Obama won the state in 2008 and 2012 with large support from black voters and young voters and they aren't behind her in full force either. That could be a problem for Clinton if they stay home or vote for a third party candidate.

Richard and Barbara Dipietro were at a rally with Donald Trump's running mate Mike Pence in York, Pa., on Sept. 29, 2016. They said Trump is tapping into the feelings of people in that area. (Meagan Fitzpatrick/CBC)

Clinton's campaign understands those two demographic groups "are really, really important," Madonna said.

That's why they have been using their best surrogates — Obama, his wife, Michelle, and Vice-President Joe Biden — in Pittsburgh and Philadelphia and often on college campuses.

Clinton is doing well with white, college-educated women in the Philadelphia suburbs, according to Madonna, but Trump is trying to win those votes.

When he announced a plan for maternity leave and child care with his daughter Ivanka beside him, he did it in Aston. It's a township 45 minutes outside Philadelphia with a population that is 94 per cent white.

Trump and the women's vote

Borick predicts Trump's efforts to get more women on board could be hampered by the release of the video where he is heard bragging about making unwanted sexual advances on women and subsequent public allegations of sexual assault.

"It couldn't be worse news as he tries to unlock Pennsylvania," Borick said. "It simply reinforces the negative views that lots of higher-educated, suburban Philadelphia women have about him."

Back on the bus with Trump supporters after the Pence rally, Ron Ives says he's voting for the Republican candidate mainly because of his promises to appoint conservative justices to the Supreme Court and tighten immigration laws.

"I'm a Trump man, he's my guy."

Can his guy win Pennsylvania? "I have my fingers crossed."