Democrats see great potential to win back control of the Senate in 2016, thanks to the kind of imbalance in the upcoming class that Republicans exploited in the previous one. Republicans will have to defend more seats, 24 compared to 10 for Democrats, some of which are in states that Barack Obama won and which the GOP candidate will likely struggle in the next presidential election. One key state in that calculation is Pennsylvania, but Democrats have found that knocking off Pat Toomey is tougher than it looks. Larry Sabato isn’t impressed with Joe Sestak, or any of the other candidates who might square off against the Republican incumbent:

The University of Virginia has released the latest edition of Sabato’s Crystal Ball, and Kyle Klondik, the project’s managing editor, isn’t especially impressed either – he’s moved Pennsylvania from a tossup in the 2016 Senate race to leaning Republican, a startling assessment given the widely held belief that Mr. Toomey is one of 2016’s more vulnerable incumbents.

Why the change? For starters, Mr. Toomey is, well, boring, and that’s apparently what we like in a senator. To be more specific, Mr. Klondik writes that the incumbent is “mild mannered and low-key,” qualities that “resonate well with the Pennsylvania electorate.” So, yeah … Mr. Toomey is dull, and we like it that way.

But we’re not especially fond of any of the alternatives, either. Democratic Party officials would come around to back Joe Sestak if he’s the nominee, but for now, the former congressman isn’t the favorite of the party, animosity that’s left over from 2010 challenge of Arlen Specter. Allentown Mayor Ed Pawlowski? His gubernatorial run last year has been practically forgotten. Montgomery County Commissioner Josh Shapiro? Who?

To answer Sabato’s question, Josh Shapiro is the man that “senior Democrats” have attempted to recruit to challenge Sestak. The problem for Pennsylvania Democrats is that most of them “loathe” the presumed nominee, who lost to Toomey five years ago:

U.S. Sen. Pat Toomey’s re-election prospects improved Thursday in one national forecast because its author says members of the Democratic establishment “loathe” challenger Joe Sestak and the other Democratic candidate’s gubernatorial campaign last year was a “flop.” …

Kondik said: “National Democrats loathe Joe Sestak,” a former congressman from Delaware County who lost to Toomey by 2 percentage points in 2010.

“The antipathy has developed for a multitude of reasons, not least his successful challenge to party-switching former Sen. Arlen Specter in a 2010 primary, as well as the fact that Sestak simply does not take direction or advice from the leadership,” Kondik said.

Shapiro himself answered Sabato’s question by removing himself from consideration. The Philadelphia Inquirer’s Thomas Fitzgerald reports on the power brokers who wanted Shapiro to come in against Sestak, too:

Senior Democrats had been encouraging Shapiro to jump into the primary against Joe Sestak, a retired Navy rear admiral and former Delaware County congressman who lost a close race to Toomey in 2010 but who also has a strained relationship with members of the party establishment.

Shapiro last week telephoned the three Senate Democrats who had been encouraging him – Minority Leader Harry Reid of Nevada; New York’s Charles Schumer; and Montana’s Jon Tester, the chairman of the national party’s Senate campaign committee – to decline. He also informed Pennsylvania Democratic Sen. Bob Casey.

If these Democratic Party leaders have to come back to Sestak, that’ll be a bit awkward, no?

Democrats need to flip five seats to wrest control away from the GOP. At this point, there are as many Republican retirements as Democratic retirements (2), with a GOP pickup potentially stronger in Nevada than for Democrats in Florida. The only really blue states in which Republicans have a large amount of risk are Illinois, Wisconsin, Pennsylvania, with lesser risk in Ohio and New Hampshire (as well as Florida, as noted above). Without Pennsylvania, it might be impossible for Democrats to win control of the Senate — and with Hillary Clinton on the top of the ticket, they can’t count on a Barack Obama-like turnout for coattails, either.