PHILADELPHIA — Hillary Clinton’s campaign is aggressively outworking Donald Trump in battleground Pennsylvania, a state the billionaire businessman can scarcely afford to lose and still hope to become president.

Despite polling well in Pennsylvania throughout the summer, Clinton’s team is nevertheless bearing down in a state her party has carried in six straight elections. They are ratcheting up advertising and dispatching their top supporters to Pennsylvania, from Bill Clinton to Joe Biden to last week’s visit from President Barack Obama.

“We’ve got to fight for this thing,” Obama thundered at a rally in Philadelphia last Tuesday. “I need you to work as hard for Hillary as you did for me. I need you to knock on doors. I need you to make phone calls. You’ve got to talk to your friends, including your Republican friends.”

At a minimum, an energized Pennsylvania campaign is a balm for Clinton as she weathers a dip in national polls and dips in the swing states of Florida and Ohio. But with roughly seven weeks until Election Day, Trump’s scattershot approach to the state also puts his White House prospects in jeopardy.

“There is no Trump turnout organization, and you can’t construct one” in the time remaining, said former Democratic Gov. Ed Rendell.

For Trump, nearly any route to the 270 Electoral College votes needed to win the White House includes Pennsylvania’s 20 votes. With Clinton’s edge in Colorado and Virginia, and her competitive standing in North Carolina, Trump could potentially win vote-rich Florida and Ohio, as well as competitive Iowa and New Hampshire, and still fall short of the White House unless he can capture Pennsylvania, too.

Clinton’s strategy is focused firmly on the eastern part of the state. Obama won 85 percent of the vote in Philadelphia in 2012, and Clinton has her sights set on coming as close as she can to his performance there while also outperforming Obama in the four suburban counties bordering the city.

Almost 2 million votes, or fully one-third of the 5.67 million presidential votes cast in the state in 2012, came from Philadelphia plus Bucks, Chester, Delaware and Montgomery counties. It’s a region replete with moderate Republicans struggling with the decision about whether to support Trump.

Obama sought them out last week as he contrasted Trump’s criticism of the nation’s path with Ronald Reagan’s “vision of freedom.” The message echoes a Clinton television spot airing in the Philadelphia area featuring Romney and Republican U.S. senators blasting Trump as unqualified for the Oval Office.

That ad is part of Clinton’s deep edge over Trump on television in the state. Her campaign and outside groups helping her have spent about $14 million on general election TV and radio ads through this week, according to Kantar Media’s political ad tracker.

That’s more than triple the advertising investment Trump and his allies made in the same time period.

One possible result of the advertising gulf is stalled support for Trump among college-educated Republicans who live in the four counties around Philadelphia. In Montgomery County, for example, nearly half of adults have college degrees compared to 26 percent statewide.

“Part of the problem he faces is he has built this wall with the college-educated voters,” Republican pollster Ed Goeas said. “As much as he’s doing better in other parts of Pennsylvania, when you talk about the suburbs, he’s struggling to reach normal Republican levels.”

That leaves Trump needing to overperform in Pennsylvania’s rural areas and working-class cities in the western part of the state. But while Trump’s running mate Mike Pence was in Scranton on Wednesday, the same day Trump’s son Donald Jr. was in Pittsburgh, each of Trump’s own three visits in the past month have been to Philadelphia or nearby.

Those visits were all small-scale campaign events, not one of the signature blockbuster rallies that make for Trump’s chief organizing tool. And as he has in other states, the New Yorker has ceded the vast majority of his get-out-the-vote efforts to the Republican National Committee.

The committee touts, as it does in all the targeted presidential states, a statewide staff dedicated to registering new voters and swaying undecided ones. But even they admit Trump faces a “challenge” putting Pennsylvania into the GOP column.

“We have always known it would be a battle in Pennsylvania,” said RNC spokesman Rick Gorka.

At Obama’s Tuesday speech, meanwhile, 100 Clinton staff members combed the crowd, armed with clipboards and smart phones, signing up volunteers to make phone calls on Saturday. They found 750, said Clinton’s Pennsylvania director, Corey Dukes.

That’s in addition to hundreds of neighborhood-level leaders and campus teams at Pennsylvania’s legion of colleges and universities, including six in Philadelphia alone. Dukes said the campaign had just signed up its first Asian and Pacific Islander coalition. It’s a smaller than those in the battleground states of Virginia and Colorado, he said, but it’s one more group signed on to deliver votes.

Clinton herself is scheduled to headline a Philadelphia campaign event Monday aimed at mobilizing young adults.

“We slice it pretty thin,” Dukes said. “Everything we do is to support getting bodies to our offices to commit to action.”

Taken together, Rendell said, the conditions are right for Clinton to amass a margin in Philadelphia and the suburbs that’s too big for Trump to top elsewhere.

“If you do the math, there aren’t enough votes in the rest of the state,” Rendell said.