That politics can be a bouncy up-and-down affair is nicely framed by a Pennsylvania poll last week with Joe Biden leading in the Keystone State, and national discussion this week about whether Biden’s done before he starts.

An Emerson Poll released Friday had Biden, who hasn’t formally announced for president, well ahead here in a large Democratic field: 39 percent support him, compared with 20 percent for Bernie Sanders, 11 percent for Elizabeth Warren, and everybody else in single digits or zippo.

No surprise, really. Biden’s a Pennsylvania native with near-universal name ID.

And since the state’s presidential primary is more than a year away, there’s no campaign here. Voters go with what they know. And they know Joe.

But he’s got problems. Beyond just his coed cuddles.

Yes, there’s the shoulders-touch, hair-sniff, top-of-the-head-kiss thing alleged by former Democratic Nevada assemblywoman, former lieutenant governor candidate, former congressional candidate, former Bernie Sanders supporter Lucy Flores.

Says she got unwelcome Biden backstage snuggling before a political rally in 2014. Got lots of attention. Not good for Joe.

And Biden’s initial statements didn’t help.

First, he said he doesn’t recall such an encounter with Flores, but believes she should be heard: “She has every right to share her own recollection.”

How generous, right?

Then came an admission of his tendency to show “expressions of affection” (really, we hadn’t noticed), accompanied by his assertion that “not once – never – did I believe I acted inappropriately.”

That’s believable. I mean, it’s believable he believes he didn’t act inappropriately.

But when one’s actions involve another person, the other person gets a say in what’s appropriate and what’s not.

The Biden pushback also includes revisiting two past “expressions of affection.” Episodes, well-aired at the time, that sure looked like unwanted Joe.

Now, Stephanie Carter, wife of former Defense Secretary Ash Carter, says Biden’s hands on her shoulders during her husband’s 2015 swearing-in was merely a “moment between close friends” and not, as often portrayed, classic creepy Biden.

Same for the seemingly get-me-outta-here response to a Biden close encounter by the then-13-year old daughter of Sen. Christopher Coons (D., Del.) at his 2015 swearing-in.

Coons tells the Washington Post his family is close to the Bidens, Joe’s known the girl all her life, and she wasn’t uncomfortable with Joe’s public display of affection.

Fair enough.

But, of course, a second woman, Amy Lappos, has come forward with another story of unsought touching. This one at a 2009 Connecticut fund-raiser, a neck-grab followed by a nose-to-nose rub from Biden that she thought was an incoming lip lock.

What are the odds there won’t be more?

Fairly or not, Biden’s tactile tendencies, no matter how he (or you) may view them, are far from pluses during #MeToo times, in a party where women’s energy and a nominee’s electability are prime driving forces.

The skeezy-touchy issue fades or vanishes in a Biden-vs.-Donald Trump general election. Neither side wants a debate on nose-rub vs. grab 'em by the you-know-what.

But it’s in play if Biden enters the Democratic primary, a contest including several women, as the party aims for a ticket appealing to women to unseat Trump.

National Republican consultant John Brabender says, “I would not be surprised if this keeps him out of the race.”

OK, but don’t Republicans fear Biden beats Trump, and want Biden out?

Maybe. But there are Democrats who fear Biden could keep Democrats home.

Their argument is times have changed, the party changed, Biden’s got baggage – past positions on desegregation, crime bills, abortion, Anita Hill – and a not-so-stellar campaign history.

“He’s got no electoral track record outside one small state [Delaware], and as a running mate to a candidate who engendered wild enthusiasm,” says a top Democratic consultant requesting anonymity due to party ties.

Also, Biden’s prior presidential runs ended quickly: dropped out in January 2008 after getting 1 percent in the Iowa caucus; dropped out in 1987, even before the election year began, following reports he plagiarized speeches.

So, the head and shoulders, nose-to-nose news won’t help a Biden rollout. But even if that news ends and passes, Biden’s got other problems to surmount for a third shot at the White House – regardless of his standing in Pennsylvania.