Donald Trump Jr. had one emphatic message for Pennsylvania Republicans on Friday: "Donald Trump is on the ticket in November."

The president's eldest son's brief remarks before GOP officials at the Hershey Lodge is part of a larger nationwide speaking tour for the 40-year-old real estate scion. Trump Jr. has criss-crossed the country this year attending fundraising and party events as the GOP gears up for a difficult mid-term fight.

Poll aggregator FiveThirtyEight currently gives Democrats a four-in-five chance of winning control of the U.S. House and a one-in-three chance of taking the Senate.

State polls, meanwhile, have shown Democratic Gov. Tom Wolf and Sen. Bob Casey with double-digit leads against their respective challenges, state Sen. Scott Wagner and U.S. Rep. Lou Barletta. Trump carried Pennsylvania by 44,000 votes, or less than 1 percentage points, in 2016.

"You have to realize: it can go away tomorrow," Trump Jr. said. "That is the other side's plan. That is their motivation."

He said the tax cuts and regulatory rollbacks that benefitted those in attendance -- Trump Jr. did not mention tariffs or the possiblity of a trade war with China in his remarks -- would be reversed if Democrats retook Congress.

But Barletta, Wagner and the slate of congressional candidates would serve as partners to help shepherd Trump's policy goals, Trump Jr. said.

"They're going to govern with my father, like my father, for all of you."

Some of the biggest laugh lines of the night came as a result of Trump Jr.'s girlfriend, former Fox News TV host Kimberly Guilfoyle, who joked about her extracurricular activities, "playing doctor" with Trump Jr.

After Guilfoyle introduced her boyfriend, Trump Jr. quipped, "I was up late last night -- not because of Kimberly. Get your minds out of the gutter."

As many as six of Pennsylvania's 18 congressional seats could flip from Republican to Democratic control, due in large part this year's new court-drawn district map.

READ MORE: 'I am not sick of winning': Donald Trump Jr. rallies the troops in Hershey | Analysis

On Friday, former President Barack Obama was also in Pennsylvania: campaigning for the state's Democrats in Philadelphia.

"I have not been here since you guys won a Super Bowl, I know," Pres. Obama says in Philadelphia. "I came here to deliver a very simple message and that is to vote. My message, Pennsylvania, is vote." https://t.co/LqoxDFnyyE pic.twitter.com/b15ukcDOWe — CBS News (@CBSNews) September 21, 2018

State GOP Chair Val DiGiorgio said that didn't intimidate him. He claimed Friday's event broke fundraising and attendance records for the party, although it occupied one of Hershey Lodge's smaller ballrooms.

"Pennsylvania will continue to be Trump country," DiGiorgio said.

Wallace McKelvey may be reached at wmckelvey@pennlive.com. Follow him on Twitter @wjmckelvey. Find PennLive on Facebook.

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