WASHINGTON — We're within 50 days of Election Day, with Pennsylvania's U.S. Senate race still close enough to go either way — and its significance growing in the national picture.
Columnist George Will recently called it "the most consequential" Senate contest in the country. That's because as other top tier races in Illinois, Ohio and Wisconsin look increasingly one-sided, the ones in Pennsylvania and New Hampshire appear likely to decide control of the Senate.
Incumbent Republican Sen. Pat Toomey and Democratic challenger Katie McGinty have been drilling their messages home for months. Here are five remaining variables that insiders and analysts in both parties say could decide the outcome:
1. Defining McGinty: McGinty has only run for office once before — in the crowded 2014 gubernatorial primary — so she's never been in this kind of spotlight and relatively few voters know her. A recent Muhlenberg College poll found that only 51 percent of likely voters had an opinion, positive or negative, about McGinty, Gov. Wolf's former chief of staff; 65 percent had a clear view on Toomey.
That presents both parties with an opportunity.
Republicans see room to fill in the blanks in voters' minds by painting McGinty as an opportunist who took advantage of her high-level government jobs — hoping to make her an unacceptable alternative to an incumbent the public already knows.
McGinty's team, meanwhile, presents her as the daughter of a blue collar Philadelphia family looking out for average workers. They believe that the many Hillary Clinton voters who don't know McGinty are far more likely to support her over Toomey once they learn more about the two candidates — giving the challenger room to grow.
Whoever does a better job shaping McGinty's image will go a long way toward victory.
2. The Trump question: Usually, you would think a sitting Republican senator would have a pretty firm stand on the Republican presidential nominee. Toomey doesn't.
He has said he won't back Clinton — but has declined to embrace Donald Trump, saying he has "concerns." It's easy to see why: Trump stirs strong feelings in many parts of Pennsylvania, and Toomey will need the conservative base to come out for him on Election Day. Speak out against him, and Trump's supporters could turn on Toomey.
At the same time, Toomey can't afford to alienate moderates in the vote-rich Philadelphia suburbs. So he has walked a fine line — but, it seems, he'll eventually have to decide which constituency he wants to risk offending.
McGinty has relentlessly pressed the issue.
3. Debates: Debates about debates are both de rigueur these days and totally inside baseball. But this one at least has a twist: The incumbent, Toomey, has pressed for more debates and the challenger, McGinty, has sought fewer.
Typically, incumbents want fewer meetings, to starve their rival of attention. But Republicans believe Toomey has much to gain from going toe-to-toe with McGinty on TV. He is skilled at distilling his arguments after having several hard-edged races under his belt. The less experienced McGinty, by contrast, has had awkward moments on the stump, including a muddled recent answer to reporters asking her views on taxes.
A debate could be the first time many voters see her live, and potentially form a lasting impression. McGinty got her way: They scheduled two debates in mid- to late-October, both seen as potential difference-makers down the homestretch.
4. Ground Game vs. air war: Among the many Republican worries over Trump is that their unconventional nominee has not built the get-out-the-vote apparatus most presidential contenders assemble. That has left other Republicans down ballot to rely on their own less famous names and less plentiful resources to drive reliably right-leaning voters to the polls.
Some Republicans are trying to change that: Americans for Prosperity, the grassroots conservative group founded by the industrialist Koch brothers, recently announced that it was canceling TV ads in Pennsylvania and elsewhere order to focus on more precisely targeted door-knocking. They hope to help defeat McGinty by reaching some 660,000 persuadable Pennsylvania voters, but they are trying to fill a void left by the biggest name on the ticket.
The Clinton campaign, by contrast, has explicitly partnered with candidates like McGinty to try to win not just the White House, but the Senate as well.
Republicans, however, appear to be building an onslaught of TV ads in the campaign's final weeks. Two independent GOP groups backing Senate candidates, the Senate Leadership Fund and its affiliated non-profit One Nation, which does not disclose its donors, recently announced a $42 million fund-raising haul. The groups have spent heavily to help Toomey, and the infusino of money comes as some big Republican donors, dismayed by Trump, turn their focus to holding the Senate in the face of a potential Clinton presidency.
So far, similar Democratic Super PACs and non-profits have hammered Toomey and helped make up for his big fund-raising edge, making this the most expensive Senate race in the country — but can they continue that down the stretch?
5. Top of the ticket: The biggest variable may be out of the candidates' hands. The results of the presidential race will go a long way to deciding how tough a road Toomey has to reelection in a state that has long gone to Democrats in presidential years.
If Trump can stay within four or five percentage points of Clinton, the thinking goes, Toomey can make up that gap with swing voters. But if Clinton's victory gets to seven points or larger, there may simply be too much Democratic momentum for Toomey to survive. Pennsylvania is seen as a critical state in the presidential race, but its outcome could reverberate down to the Capitol as well.
You can follow Tamari on Twitter or email him at jtamari@phillynews.com.