Hillary Clinton asked Philadelphia congregants to "honor me with your vote" as she visited two African American churches in the city Sunday morning, campaigning just ahead of a Pennsylvania primary that could all but seal her grip on the Democratic nomination for president.

Hispanic supporters of Bernie Sanders, meanwhile, gathered in Reading while the Republican campaigns prepared to tackle the Pennsylvania GOP's convoluted delegate system as Tuesday's much-watched primary loomed.

The Keystone State will be the biggest prize when voters in five Northeast states go to the polls, a position reflected by a wave of activity in the past week as Clinton and Republican front-runner Donald Trump each seek to notch another big-state win to follow their recent victories in New York.

Rivals are running out of time to stop them.

Clinton, whose father was from Scranton and who has deep political ties to the state, was the only candidate in Pennsylvania on Sunday.

At the churches, she touched on reforming the criminal-justice system, honoring Harriet Tubman, and continuing President Obama's work. She called for "more respect, more kindness, more love."

Polls give her a sizable lead over Sanders in Pennsylvania, including an NBC News/Wall Street Journal/Marist survey released Sunday that showed the former secretary of state up 55 to 40 percent among likely Democratic voters.

Former President Bill Clinton also came seeking support for his wife - in the form of campaign checks - at an afternoon fund-raiser in Wynnewood.

Gov. Wolf, Sen. Robert P. Casey Jr., former U.S. Rep. Allyson Y. Schwartz, and other top Pennsylvania Democrats joined him, along with director Lee Daniels, under a white tent on the lawn of a lawyer's three-story stone mansion.

Tickets cost $1,000 per person. At the event, Casey warned of the "great challenge ahead" for Hillary Clinton in the fall election.

Earlier, in a much different setting in North Philadelphia, Clinton's surprise visit brought churchgoers to their feet at the sprawling Triumph Baptist Church.

Clinton promised to fight for tougher gun laws and touched on last year's church shooting in Charleston, S.C. Less than 20 miles from where she spoke, a shooting at a Montgomery Township church left a man dead Sunday..

Her host, Rev. James S. Hall Jr., said he is careful not to tell his congregation how to vote, but "I'm just going to prophesize that Hillary is going to win."

Clinton later entered the historic African Episcopal Church of St. Thomas to the singing of "Battle Hymn of the Republic." Within the Overbrook church's stone walls and stained-glass windows, the candidate spoke to congregants - and received a sprinkling of holy water.

Jennifer Caviness of Mayfair watched alongside her daughters, ages 3 and 6 months. "A lot of the things [Clinton] talked about were easy to relate to because we have young kids," she said.

The day's events reflect an unusual year that has kept presidential campaigns churning deep into primary season - making Pennsylvania's relevant despite its late voting.

Sanders on soda tax

Campaigning in Rhode Island on Sunday, Sanders spoke about Philadelphia's proposed soda tax, labeling it "totally regressive" on NBC's Meet The Press and saying it would hit lower-income consumers hardest. Clinton has praised the idea, which Mayor Kenney is pushing to help fund universal prekindergarten.

Clinton's allies - led by Sen. Cory A. Booker (D., N.J.) - blanketed the area. Sanders picked up support from former Philadelphia Mayor Bill Green, who in a letter to the Inquirer called Sanders' rejection of money in politics "desperately needed chemotherapy" for "a cancer at the heart of our republic."

In Reading, actress Rosario Dawson joined a few dozen local Latino activists to back Sanders, building off his call last week to close the Berks County Residential Center, which critics say detains immigrants who broke no laws and are seeking asylum.

Though Sanders has struggled to sway minority voters, those in Reading lauded the Vermont senator's work.

"He has stood up for the rights of immigrants and for fixing our broken immigration system for years," said Adanjesus Marin, who leads the Working Families PA political action committee and is working with activists to close the detention center.

West Reading Mayor Valentin Rodriguez, an independent, said Sanders' message of fighting economic inequality "resonates in the Hispanic community."

Sanders is due back in Pennsylvania on Monday, with visits to Pittsburgh in the morning and Drexel University in the evening.

None of the Republican presidential candidates scheduled public events in the Philadelphia area Sunday.

The same poll that had Clinton leading gave Donald Trump a big edge: 45 percent support among likely Republican voters, compared with 27 percent for Ted Cruz and 24 percent for John Kasich.

Even if Trump scores another win in Pennsylvania on Tuesday, however, the number of delegates he would gain remains a question.

That's because of the state GOP's unusual allocation process - which leaves 54 of 71 delegates unbound, even after Tuesday's voting.

Cruz's camp has fielded a slate of 26 delegate candidates who say they are loyal to the Texas senator, and has been credited by party operatives as the most organized in the state.

Trump, however, has a team of 41 delegate candidates - and blasted out that list to his 7.7 million Twitter followers Saturday.

On Sunday, Trump backers gathered at campaign offices in Conshohocken and elsewhere for training on how to spread the word about their candidacies. They plan to hand out information at the polls showing which delegate candidates back Trump.

Many other delegate candidates, though, are allied with the Republican party apparatus, and say that on the convention's first ballot, they will support whoever wins the popular vote Tuesday in their congressional district - but that they will keep an open mind if no one can secure the nomination on the first try.

After that, many say they will focus on "electability."

That language points to Kasich, the Ohio governor who has made the case that he gives the party its best chance to beat Clinton, despite lagging in primary contests.

Polls, including the one out Sunday, consistently show Kasich performing the best in a hypothetical matchup in Pennsylvania against Clinton.

The Senate race

Campaigning in a much tighter Pennsylvania primary that also has national implications, Wolf on Sunday joined Senate candidate Katie McGinty as she whisked through Philadelphia.

McGinty, Wolf's former chief of staff, and former U.S. Rep. Joe Sestak are neck and neck in the fight for the Democratic nomination. The winner will challenge Sen. Pat Toomey (R., Pa.) this fall in a contest both parties say could help decide control of the Senate.

Sestak on Sunday kept up his tradition of visiting black churches, something he credits for driving turnout on his behalf, even when much of the Democratic establishment has opposed him.

Democratic insiders expect that race to go down to the wire.

Also in the contest are Braddock, Pa., Mayor John Fetterman, who has lagged in polling, and Western Pennsylvania spring manufacturer Joseph Vodvarka, who was restored to the ballot last week after overcoming a challenge to his petition.

@JonathanTamari

Politics writer Thomas Fitzgerald contributed to this article.