HARRISBURG — With Democrats stoking an anti-Trump furor, Pennsylvania’s election brought good news for the party ahead of a big election in 2018 that will feature contests for governor and U.S. Senate.

Democrats scored big victories in county and municipal races across Philadelphia’s suburbs, advancing a decades-long shift in those one-time Republican bastions where President Donald Trump lost heavily last year. Just to the north, Democrats took control in Northampton County, won by Trump last year.

Delaware County’s Democratic Party chairman, David Landau, said the strength of his party’s victories up and down the ballot reminded him of the post-Watergate election in 1974.

“That’s the only kind of comparable tsunami that you can think of, where we’d just won everything,” Landau said.

The party won two seats on county council, the first such victory since 1980 when the county last guaranteed a seat to the minority party. It also flipped control of Upper Darby, Pennsylvania’s sixth-most populated municipality.

The county party had absorbed a wave of volunteers starting just after last year’s election, when Pennsylvania backed a Republican for president for the first time since 1988 and helped Trump capture the White House.

Pennsylvania’s Republican Party chairman, Val DiGiorgio, said he knew it would be a tough night in Philadelphia’s suburbs, but he also did not anticipate what he called a “tidal wave” of Democratic voters. Democrats, he said, were frustrated with national politics.

“It wasn’t because of the local candidates,” DiGiorgio said.

There still were bright spots for Republicans. The GOP’s candidate, Sally Mundy, won an open seat on the state Supreme Court — albeit with support from traditional Democratic Party allies, including trial lawyers, the Service Employees International Union and Pennsylvania’s largest teachers union.

Four Democrats and three Republicans — all women — led in contests for seven open seats on Pennsylvania’s appellate courts, a place where women are increasingly well represented.

Next year’s election will be big for Pennsylvania, where Democrats hold an 800,000-voter registration advantage over Republicans, or a four-to-three edge.

Franklin and Marshall College pollster and public affairs professor Terry Madonna said it is too early to draw conclusions about the course of next year’s general election, based on Tuesday’s election results.

But, he said, there was a clear connection to a growing voter dislike for Trump’s job performance, and it puts Republicans on the spot over how closely their candidates should identify with Trump.

“The Republicans have a major challenge in front of them,” Madonna said. “What do they do with President Trump?”