HARRISBURG — Barely half of the Pennsylvania Republicans in Congress have made the short trip into neighboring Ohio to attend the party’s convention.

Among those who’ve decided to stay home is U.S. Sen. Pat Toomey, who is in the midst of a re-election campaign against Democrat Katie McGinty.

Toomey said he is better served spending the week traveling the Keystone State and meeting voters.

“There are only a handful of Pennsylvanians in Cleveland,” he said at a stop in Johnstown Tuesday.

The light showing at the convention isn’t just a Pennsylvania phenomenon, said G. Terry Madonna, a political science professor at Franklin and Marshall College who is attending the convention, with only 6 of 13 Republican House members from the state.

Former presidents George W. Bush and George H.W. Bush are skipping the convention. So are the last two Republican nominees — John McCain and Mitt Romney.

Ohio Gov. John Kasich, who campaigned against Donald Trump for the party’s nomination, didn’t come to the convention even though it’s in his state.

Kasich was scheduled to visit with Pennsylvania Republicans on Wednesday but cancelled the appearance a day earlier.

“I don’t think you can rule out that there are a lot of Republicans who are not behind Trump,” Madonna said. “It’s not a coincidence.”

But, despite media coverage highlighting the anti-Trump movement, he noted, “This is a Trump convention.”

“Make no mistake about it,” he said, “these delegates are enthusiastic.”

The question coming out of the convention will be whether Trump can broaden his appeal.

In Pennsylvania, seen as a swing state to be hotly contested between Trump and Democrat Hillary Clinton, that will mean winning against odds stacked against the GOP.

There are 1 million more registered Democrats than Republicans in Pennsylvania, and another 1 million independent voters.

Whether the absence of members of Congress from the Lehigh Valley and southeastern Pennsylvania reflects the mood of voters in those areas will become clearer in the weeks ahead.

But Trump needs to do well in those areas to beat Clinton in the fall, Madonna said.

“He’s got to win the Philadelphia suburbs,” he said.

Former U.S. Rep. Phil English, attending the GOP convention as a delegate, said unless a member of Congress has a speaking gig, there isn’t much value in going to the convention except to raise money.

“I don’t think it’s significant that many are not here,” he said.

Incumbents threatened by a challenger for reelection often decide it’s better to spend the week campaigning at home.

English did just that in 2008, skipping the convention in St. Paul, Minnesota, that nominated John McCain. At the time, he was embroiled in what proved a losing bid to keep his seat in Congress.

Others at this year’s convention said the ambivalence of establishment Republicans may have less to do with Trump’s appeal among voters, and more to do with their concern about getting behind a non-traditional candidate.

“Politicians, as a rule, are strange,” said James Klein, a pro-Trump delegate from Pennsylvania’s 5th Congressional District. His congressman, U.S. Rep. Glenn Thompson, is also in Cleveland this week.

State Sen. Mario Scavello, R-Mount Pocono, said Trump appeals to many new voters who previously had no interest or faith in the politics. 

He described talking to a 90-year-old woman who hasn’t voted in more than 15 years but said she is backing Trump.

“When you have people that energized, you don’t know what to expect,” he said.

Scavello is attending the convention a delegate from Pennsylvania’s 10th Congressional District, which is represented by U.S. Rep. Tom Marino, one of the first members of Congress to support Trump.

In addition to Thompson and Marino, other Pennsylvania congressman attending the convention were 

Those who making the trip were: U.S. Rep. Mike Kelly, R-3, U.S. Rep Bill Shuster,  R-9, U.S. Rep. Lou Barletta, R-11 and U.S. Rep Keith Rothfus, R-12.

John Finnerty covers the Pennsylvania Statehouse for CNHI’s newspapers and websites. Reach him at jfinnerty@cnhi.com and @cnhipa on Twitter.