I’ve written previously about how Pennsylvania’s 2016 Senate race will be competitive since the Keystone State is one of the foundations of the proverbial Northeastern blue wall that’s a lock for Democrats in national elections. While incumbent Republican Sen. Pat Toomey would still beat Democratic Joe Sestak by a four-point margin in an early left-leaning PPP poll, he still could face hurdles in the areas where elections are decided in Pennsylvania; collar counties around Philadelphia and Allegheny County (aka Pittsburgh).

Here are the 2010 results from those counties:

Toomey lost Allegheny County [Toomey-192,257 Sestak-232,996]–where Pittsburgh resides–in 2010, Montgomery County by 23,458 votes [Toomey-131,955 Sestak-155,413], and Delaware County [Toomey- 89,955 Sestak- 113,844] by 24,889 votes, but won Bucks County [Toomey -121,331 Sestak- 107,208] by a little over 14,000 votes. Yet, all three counties have voted Democratic since 1992­–and all three have more registered Democrats than Republicans.

As for Allegheny County, the voter registration there is almost 60 percent Democratic–and the last time the county went Republican in a presidential race was in 1972. Yet, it’s not impossible to be a Republican and win in Allegheny; Tom Corbett was able to beat Democrat Dan Onorato by a meager 460 votes in the 2010 gubernatorial race.

Democrat Tom Wolf beat Corbett in 2014.

Toomey needs to win at least one collar county around Philadelphia in 2016 to clinch re-election; having a solid showing in the other two counties couldn’t hurt him either. Yet, in a presidential year, the increased turnout could be an obstacle. In the county where Toomey won in 2010–Bucks–228,539 ballots were cast in the election. In the 2012 Senate race, 307,853. Incumbent Democrat Bob Casey won handily that year. Montgomery, the most populous county, saw 287,368 total ballots cast in the 2010 senate race, but 399,079 were counted in 2012.

In 2016, Toomey won’t be riding a Tea Party wave; he’ll be trying to maintain his balance on Hillary’s (supposedly), which could drive those voter numbers higher–and in the opposite direction. Yet, for now, he has a solid lead over Sestak in a new Quinnipiac poll (via The Hill):

Sen. Pat Toomey (R-Pa.) begins his 2016 reelection efforts with a big lead over former Rep. Joe Sestak (D), according to a Quinnipiac University poll released on Monday.

The survey shows Toomey taking 48 percent support compared to 35 percent for Sestak.

Voters in Pennsylvania have largely positive views of Toomey. Forty-nine percent say he’s doing a good job, compared to 24 percent who say he isn’t. In addition, 44 percent view him favorably, while only 23 percent have an unfavorable view of the senator.

Sestak, meanwhile, suffers from low name recognition. Sixty-one percent of Pennsylvania voters say they don’t know enough about him to have an opinion.

“It’s an uphill fight for Joe Sestak who has to chip away at U.S. Sen. Pat Toomey’s approval numbers while trying to win over Pennsylvanians who just don’t know enough about him,” Tim Malloy, assistant director of the Quinnipiac University Poll, said in a statement.

The sample of the poll consisted of 1,036 registered PA voters, with no D or R advantage.

So, it’s not a too shabby start, especially since Toomey is winning independents and women voters.

Nevertheless, Pennsylvania is something of a cruel mistress, a unicorn that Republicans can’t seem to catch. Despite having a Republican-dominated legislature, along with the majority of the county courthouses also being Republican, the rural vote is simply not enough to win statewide. Toomey will surely lock up the “T” portion on the state, but he has his work cut out for him in the collar counties. He could fare better due to the power of incumbency and the fact that he’s reportedly moved towards the center since 2010.

Oh, and Democrats really don’t seem all to thrilled about Joe Sestak running in 2016. After all, he did cost Democrats a Senate seat. They seem to be looking to Phildelphia District Attorney Seth Williams, but the Democratic Senatorial Campaign Committee (DSCC) is still open to backing Sestak (via National Journal):

Anxious about a candidate considered to be an unreliable maverick and a political liability, Democratic Party leaders have undertaken a quiet, intensive search in recent months to recruit a serious primary challenger to former Rep. Joe Sestak, the party’s Senate nominee in 2010 who is again running for Pennsylvania’s Senate seat.

The effort has involved former congressmen, state senators, county leaders and, recently, even a prominent district attorney. Their anxieties are being driven by party officials, who are concerned that Sestak could cost Democrats a must-win state in 2016. They’ve yet to turn up a successful alternative, but in their telling, it’s only a matter of time before a new challenger—one with the backing of the party establishment—enters the race.

“[Sestak’s] not scaring anyone,” said Bob Brady, a congressman from Philadelphia and behind-the-scenes power player in Pennsylvania Democratic politics. “He’s not clearing the field because he’s running.”

The concern over Sestak is multifaceted. Party insiders fear he’s a loose cannon and doubt he will listen to the advice of political professionals. That’s a necessity in what will be a hard-fought race against Republican Sen. Pat Toomey, an outspoken fiscal conservative who has effectively shifted to the political center since taking office in 2011.

But there’s also a personal animus toward Sestak, known to party leaders as a political loner who defied the Democratic establishment in 2010 when he ran against Arlen Specter. That year, against the advice of party leaders, he challenged the party-switching senator in the primary—and prevailed, even though President Obama, Gov. Ed Rendell, and the Democratic Senatorial Campaign Committee were against him.

…

“In my estimation, if Joe Sestak is the nominee in 2016 for U.S. Senate, we will once again lose to Pat Toomey,” said T.J. Rooney, who was state Democratic Party chairman when Sestak ran in 2010.

…

But in recent weeks, another intriguing name has surfaced as a potential candidate, someone who until recently was on few people’s radars: Seth Williams, the district attorney of Philadelphia.

The 48-year-old, Philadelphia’s first black district attorney, told National Journal he’s focused on his current job. But he didn’t discount the possibility that he might be interested in seeking higher office.

“Who wouldn’t want to be a U.S. senator?” Williams said. “I really believe if we want to make the city safer, to prevent crime, we need to create more early-child education opportunities, and increase economic opportunities for individuals and businesses. And being a senator would allow me a great opportunity to let me do all of those things.” He added: “I’m a member of the Pennsylvania National Guard, so I take orders well. If they give me a call, I’ll listen.”

Williams has a profile that could excite some Democrats: A former student leader at Penn State, he’s served in the military and tangled with embattled state Attorney General Kathleen Kane over a public-corruption investigation into fellow Democrats. Just this week, he’s blasted the state’s newly elected Democratic Gov. Tom Wolf for issuing a moratorium on the death penalty in Pennsylvania.

But along with his centrist credentials, Williams could become the first black senator in Pennsylvania’s history—which could motivate liberal and African-American voters to turn out in a race many Democrats see as a base election anyway.

Again, it’s early, but it should give Republicans some confidence knowing that one of the many incumbent Republicans in blue to purple states running for re-election next year has a solid showing in the initial polls.  The question is if Toomey can tread water long enough to survive.