Deep into a cold March night in tiny Ligonier, Pa., Joe Sestak padded through a Ramada Inn in his socks, reviewing papers and talking up the sleepy front-desk staff.

Sestak - who sleeps little and eats even less - was opening a manic run to win the Senate seat that eluded him in 2010, walking 422 miles across the state more than a year before the first vote is cast.

In Washington, the Democratic Party establishment rolled its eyes and dialed up alternatives.

They landed on Katie McGinty, a sunny mother of three with years of experience in the White House and Harrisburg, respect from party insiders, but only one run for office - a last-place bid for governor in 2014.

With few policy issues to separate them, their critical showdown in next week's primary has become a test of insider muscle against outsider uprising - with hints of the same contrasts roiling the presidential race.

Party powers from President Obama to Gov. Wolf to steelworkers and teachers unions have lined up behind McGinty, Wolf's former chief of staff.

Sestak, defiantly independent, says his support comes from the grassroots, not insiders. The former congressman and three-star admiral vows to restore trust in political leaders.

On the edges looms Braddock Mayor John Fetterman, a wild card who presents himself as the voice of authenticity, much like Bernie Sanders.

For both parties, the stakes are huge and extend beyond Pennsylvania: The winner will challenge Republican incumbent Pat Toomey in a contest that could determine control of the Senate.

Sestak has consistently led the polls.

Party leaders insist that McGinty is their best option - and are spending big to convince voters. Washington-based groups have pledged more than $3.3 million for ads to pull her across the finish line.

Sestak says they are trying to buy the race.

Both sides believe it is tightening in its final days.

Katie McGinty Her turn?

McGinty's visit to North Philadelphia this month gave a telling snapshot of much of her campaign: tightly controlled and with McGinty's supporters, rather than the candidate, taking center stage.

At E.W. Rhodes Elementary School, McGinty, sparkling in a blue skirt suit, stands with teachers union leaders and two City Council members. She greets a school staffer who wanders by with a welcoming hand on the shoulder.

The union heads lavish her with praise - and take shots at Sestak.

A day earlier, McGinty, 52, beamed alongside Vice President Biden at a Pittsburgh diner. And when rivals attack McGinty on trade or fracking, she points to the labor unions and environmental groups that support her.

She says the endorsements show she shares the values of party leaders and the working class, and has fought for them during her time in government. "They see in me a person who jumps into the arena, rolls up my sleeves, and gets stuff done," she says at the Philadelphia school.

But in a year of anger over typical politics, some insiders question how far establishment backing can go. For months, McGinty has remained little known.

"That's a powerful group to back you, but it hasn't translated, at least yet, into polling numbers," said Chris Borick, a Muhlenberg College analyst.

Fetterman, echoing what some operatives say privately, calls her scripted. The millions needed in outside help, he argues, shows her soft support.

Her backers say McGinty just needs a chance.

"Her background, her energy level, her ability to connect, her ability to work with people - she's a very, very, very good candidate," said Sen. Jon Tester of Montana, chairman of Democrats' national Senate campaign arm. "The polls are a matter of a lack of awareness of who Katie McGinty is."

Even Sestak allies acknowledge the appeal of a candidate vying to be Pennsylvania's first female senator, possibly running alongside Hillary Clinton.

EMILY's List, which backs Democratic women who support abortion rights, is spending $1.75 million on McGinty's behalf, nearly all of it to attack Sestak. National Democrats are adding $1.5 million.

"It's pretty amazing for a party committee to be intervening in a primary in this fashion," said Kyle Kondik, managing editor of Sabato's Crystal Ball, a political analysis site. "It's not particularly obvious to me that McGinty is way stronger than Sestak."

McGinty says the momentum is on her side as undecided voters tune in. She hopes they will hear her latest ads, proudly blaring Obama's endorsement.

Joe Sestak A whirlwind

In his signature olive bomber jacket, Sestak bursts into the Delaware County Democratic gathering long after the chicken dinners have been served.

His April speech to the crowd in Drexel Hill is from his own script: thick with Navy metaphors and veering between themes. He even cuts off his own lines.

"You've taught me . . . that national security begins at home, in our health, our education, our economics. . . . But what you most taught me comes from a wonderful religion, even though I'm a Catholic," he tells them.

No matter. Sestak leaves as abruptly as he arrived, to a standing ovation.

To supporters, his rambling energy means Sestak is seemingly everywhere. The 64-year-old hands out his cellphone number and promises follow-ups to everyone he encounters.His campaign touts the 18,000 constitutent cases his congressional office handled.

His unorthodox approach won him two terms in Congress, a 2010 primary upset over Sen. Arlen Specter and brought him within two points of Toomey.

It hasn't won him friends. The former Navy officer has a reputation as obstinate, unwilling to take advice or help others in the party.

His off-the-cuff, sometimes clumsy style scares political professionals.

Republicans once posted a blooper reel showing Sestak knocking over two children as he careened through a parade. McGinty allies pounced when he told a newspaper he wouldn't want to win in "a prostituted way."

And some Pennsylvania Democrats worry that big donors will look elsewhere if he wins the primary.

Sestak has long thrived on his own counsel, though, and says the party shunned him after he refused to take orders from Senate power brokers.

"There are people who are leaders and there are people in positions of power," he says. "My party, I fear, is more worried about control and power and a vote rather than people who can galvanize people."

Like McGinty, he has outside help: A super PAC bought $750,000 in ads for him, but it is almost broke.

He'll be outspent, and attacks are raining down.

That's why he says he did his walk and a policy tour: so he's not introducing himself in the final days, but reaching voters who already know him.

"We'll just constantly get out there," he says. "Every day we drop 8,000 brochures."

John Fetterman Fan favorite

The crowd at the Fishtown brewpub is young, liberal, urban. They rave about Sanders - and Fetterman.

Joey McAteer hands the mayor a Sly Fox stout. "It's not that often that you listen to someone and you believe them, as a politician," says McAteer, 38.

Nearly everyone wants a picture with the hulking, tattooed mayor from a struggling former steel town. Fetterman, 46, lacks the money or connections of his rivals, but hopes his unvarnished persona can upset the political order.

In the black mechanics shirt he wears to debates and ritzy political gatherings, he says he wants a national platform for what he has done in Braddock, helping people struggling with crime, poor schools, and economic change. His speech at the Interstate Drafthouse goes just 2 minutes, 50 seconds. He doesn't do ballrooms.

"We want to be where people would be normally anyway - having fun, doing their thing, because that's the kind of campaign that we are," he says. Along with issues, "it's also about being real."

Odds are long: He lags in money as Sestak and McGinty bombard the airwaves in a final sprint.

For whoever wins, Toomey awaits, with more than $9 million in the bank.

@JonathanTamari

Staff writer Caitlin McCabe contributed to this article.