US President Joe Biden headed Thursday to Pennsylvania to campaign alongside Senate hopeful John Fetterman, whose closely-watched race could prove key to avoiding a Democratic wipeout in the midterms.

Biden touched down first in Pittsburgh, where he touted his signature infrastructure package with a tour of a newly repaired bridge, ahead of an evening fundraiser with Fetterman in Philadelphia.

Fetterman, who greeted Biden on the tarmac in Pittsburgh, is one of the most unusual-looking figures on the campaign trail, with multiple tattoos and a love of hoodies and cargo shorts.

He was once a runaway favorite in the battle against Republican candidate Mehmet Oz, a celebrity TV doctor -- but the race has tightened, reflecting sinking Democratic hopes of maintaining the party's already fragile control of Congress.

The Democrat suffered a stroke in May and the Oz campaign has made his health a major campaign issue, arguing that he is medically unfit for office.

Fetterman's doctor released a letter this week stating that he could work "full duty" in public office. The two candidates are scheduled to hold a live debate on October 25 and Fetterman's performance will be scrutinized for any signs of physical or cognitive weakness.

The latest average of polls shows Fetterman's nearly 11-point lead in mid-September whittled down to about five points.

Analysts say Pennsylvania is among a handful of races Democrats must win to keep the Senate after November 8, while the tussle for the House is even tougher.

Biden, hampered by approval ratings in the low 40 percent range, has not been much help. Some Democratic candidates have even declared him a hindrance, asking him to keep away.

In a break with tradition, Biden has avoided large-scale rallies in favor of more intimate gatherings and policy announcements that he hopes can shift the momentum. Just this week, he gave speeches vowing to protect abortion access and explaining his attempts to tamp down high energy costs.

But three weeks from voting day, Americans appear to be veering toward the Republican message that Democrats are failing on the economy.

That raises the likelihood of Republicans taking control of at least the House and quite possibly the Senate -- ushering in two years of political trench warfare for the White House.

And even just the House would give the increasingly far-right Republican Party the ability to shut down Biden's agenda and -- as prominent figures are already threatening -- attempt impeachment.

 

- Numbers don't add up -
 

A New York Times/Siena poll this week showed that, of likely voters, 26 percent named worries over the economy as their top issue, while 18 percent listed inflation, at its highest rate in four decades.

That is not something Biden can fix quickly. This week also saw Bloomberg's latest probability model giving a 100 percent chance of a recession in the next 12 months.

Even on issues where Biden feels he has a winning hand, there are limits.

During his impassioned speech on abortion, the president tapped into widespread anger over the Supreme Court's decision to overturn the half-century-old Roe v. Wade ruling that enshrined national abortion rights.

Predicting a revolt by women voters at the ballot box, Biden said Republicans "ain't seen nothing yet."

But the Siena poll does not bear that out: just five percent of likely voters named abortion as their top issue.

Parties controlling the White House nearly always suffer a loss of seats in Congress during midterms, so a heavy Democratic loss would be no surprise.

Analysts with Larry Sabato's Crystal Ball election newsletter at the University of Virginia said that after giddy hopes of somehow defying gravity, the Democrats seem to be coming back to earth.

"The usual midterm headwinds remain for Democrats. It's just tough for a party to thrive with an unpopular president and with the public having significant concerns about issues, like the economy and inflation," they said Wednesday.

"This is why the House remains very likely to flip to the Republicans and why, despite the aforementioned challenges, Republican chances to win the Senate remain no worse than a coin flip."