WASHINGTON (Reuters) – U.S. President Donald Trump on Thursday will travel to the area in the swing state of Pennsylvania where Democratic rival Joe Biden was born to slam his decades of government service, hours before the former vice president accepts his party’s nomination.The speech, which the campaign has said will highlight a “half century of Joe Biden failing America”, will seek to shore up the Republican’s support in the state, which may prove key to winning re-election in November.

Trump won the rust belt state of Pennsylvania by just 45,000 votes in 2016, and is trailing Biden in recent polls there by about six percentage points, according to Real Clear Politics.

But the speech in Old Forge, Pennsylvania, on the outskirts of Biden’s birthplace of Scranton, could also backfire, according to Politics Professor Terry Madonna at Franklin and Marshall college in Lancaster, Pennsylvania.

“He is going to have to be careful about what he says about Joe Biden given Scranton is his hometown,” Madonna said. He said that Trump should focus his message on bringing jobs back to blue collar areas, which worked in 2016, and try to shore up confidence in his handling of the deadly coronavirus pandemic.

“How far he could go with (the criticism) is anybody’s guess. But Trump is Trump and he’s going to do what he does,” he added.

Biden, who moved to Delaware when he was young, will accept the presidential nomination on Thursday night, closing out a four-day virtual Democratic National Convention where speakers have argued that he can unite the country after four years of Trump’s divisive leadership.

Biden consistently beats Trump in national polls on who could better handle the pandemic, which has killed more than 170,000 Americans. Trump routinely bests him on managing the economy, however.

The Pennsylvania speech caps a week of appearances by Trump to counter the convention, which has included speeches from some prominent disaffected Republicans, ahead of the Republican National Convention next week.

On Monday, Trump traveled to Mankato, Minnesota, and Oshkosh, Wisconsin, where he boasted of his strong record on jobs growth and vowed to restore the economy ravaged by shutdowns to curb the coronavirus.

In Yuma, Arizona, on Tuesday, Trump touted progress building a wall across the Southern border with Mexico, highlighting his anti-immigration and law-and-order messages, a key plank of his successful 2016 bid.

Despite his ebbing support in Pennsylvania, Trump’s campaign is confident he will clinch it a second time on Nov. 3.

“Biden’s socialist agenda would kill jobs and hurt families in the Keystone State, which is exactly why he won’t confront voters in his hometown,” deputy national press secretary Samantha Zager said in a statement.

“President Trump has a record of success to point to in Pennsylvania, and voters in the state will reelect him this November as a result.”