WASHINGTON - For Republicans, Donald Trump is now unavoidable.

But the reaction to his impending nomination - effectively sealed this week when his last GOP rivals abandoned the presidential race - was split among Pennsylvania and New Jersey Republicans likely to appear on the ballot with him this fall.

Two Philadelphia-area congressmen who represent moderate districts jumped on board Wednesday, saying they would back their party's nominee in an effort to beat Hillary Clinton.

Others, however, kept their distance, including Sen. Pat Toomey (R., Pa.), who faces the region's most difficult and pivotal reelection battle, and might be most affected by the top of the ticket.

Toomey's campaign did not respond to questions Wednesday about whether the senator would support Trump.

The divided response reflects the dilemma Republicans have faced for months: worrying that Trump could turn off the swing voters - or even some Republicans - needed to win moderate congressional districts and Pennsylvania's critical Senate race, but also fearful of alienating the many voters Trump has energized.

"He has a great deal of work to do to convince many Americans, myself included, that he is prepared and able to lead this great nation," Rep. Charlie Dent, an Allentown Republican and prominent House centrist, said in a statement.

Dent questioned whether Trump could win, given his low approval ratings with Hispanics and women. He also said he was "extremely concerned" about his rhetoric, divisive comments, and "sparse - and often conflicting - policy positions."

On the other side, Reps. Ryan Costello of Chester County and Tom MacArthur of South Jersey each now plans to back Trump, despite representing the kind of affluent districts where many fear the New York businessman's abrasive style could potentially sink down-ballot Republicans.

"Donald Trump is my party's presumptive nominee and I intend to support him," MacArthur said in a statement. MacArthur had criticized the tone of the GOP primary, but cited the importance of beating Clinton. "My goal is to work with [Trump] and all Republicans to heal the party and present an optimistic vision that appeals to the American people," he said.

A Costello aide echoed the thought, calling it "vital" for Republicans to win in November.

Still silent, however, is Toomey. For months, the senator has pledged to support the Republican nominee, but he has avoided naming or backing Trump.

He skipped a Trump-led fund-raiser for the state GOP. He endorsed Sen. Marco Rubio for president and, when Rubio withdrew, voted for Ted Cruz in the primary. He has taken pains to avoid being lumped with Trump.

"I'm going to be running a separate campaign," Toomey said last week. "I have my own record and I have my own future."

His challenger, Democrat Katie McGinty, is eager to argue otherwise. "Pennsylvania voters will have a clear choice between the misguided policies backed by Trump and Toomey, and Katie's plan to strengthen the middle class," her spokeswoman said Wednesday.

The same strategy is in play in other Philadelphia-area seats. Democrats have blasted out releases tying Trump to Republicans who are running, such as Bucks County congressional candidate Brian Fitzpatrick.

"Guilt by association will be the Democrats' strategy," said Michael Federici, a political scientist at Mercyhurst University.

Republican leaders for months have urged its congressional candidates to run on local issues, separating themselves from Trump.

Rep. Patrick Meehan of Delaware County said in a statement, "I'm focused on my race and an agenda for families in Pennsylvania." He did not say whether he would back Trump.

As Trump has surged to victory - including sweeping all 67 Pennsylvania counties in last week's primary - more Republicans have embraced him.

At least seven members of Congress from Pennsylvania and one House nominee have publicly backed him.

Rep. Mike Kelly, from Pennsylvania's northwest corner, "plans to strongly support" Trump, a spokesman wrote in an email.

"He will attend the convention in July to help unite his colleagues and remind them of the consequences of losing a third general election in a row," wrote Thomas Qualtere.

Three other Pennsylvania congressmen, Tom Marino, Lou Barletta, and Bill Shuster, all previously endorsed Trump, and Rep. Keith Rothfus will also support him, a spokeswoman wrote. So will Lloyd Smucker, a state senator running for a Lancaster County-based House seat, who cited the need to beat Clinton.

Barletta, Trump's campaign cochair in Pennsylvania, said the enthusiasm for the billionaire - especially among blue-collar voters who might normally support Democrats - has created "a good opportunity" for down-ballot Republicans.

The support may only go so far: Several candidates or nominees, including Dent, Smucker, and Rep. Scott Perry, said they won't attend the GOP convention in Cleveland, though an aide said Perry would support the party's nominee.

Skipping the convention can help candidates demonstrate their independence, said John Brabender, a GOP consultant. Attending, he said, means you may be held accountable for everything that happens there - even though the individual candidates have little say over the program.

Federici, the Mercyhurst analyst, said it's time to stop underestimating Trump. He noted that when celebrating his latest win Tuesday night, Trump took on a more contrite tone, seeming to pivot toward a general-election audience.

"The better job that he can do in remaking himself into a more presidential Donald Trump," Federici said, "the more likely it is Republicans down the ticket will support him and not see him as a liability."

jtamari@phillynews.com @JonathanTamari