Pennsylvania insiders agree the results of today’s Member-vs.-Member primary are as unpredictable as the weather in southwestern Pennsylvania, where the overnight forecast was calling for as much as 8 inches of snow.

“It’s snowing in Pittsburgh now,” Larry Ceisler, a veteran Democratic consultant, said Monday afternoon. “If there’s very bad weather in western Pennsylvania tomorrow, then I think it could have an effect on” the race between Democratic Reps. Jason Altmire and Mark Critz.

The highly anticipated Altmire-Critz primary is just one of two competitive contests for Congressional Democrats in the Keystone State. In northeastern Pennsylvania, veteran Rep. Tim Holden faces a tough primary in the 17th district against wealthy attorney Matt Cartwright.

For these Members, the bad weather means their field and get-out-the-vote operations matter more than ever.

Democrats initially viewed Altmire as the frontrunner in the race because the redrawn 12th district includes about 65 percent of his current territory. The three-term Congressman released a poll earlier this year showing him with a 24-point lead.

But the race tightened significantly in the closing weeks. Last week, an independent poll from Tribune-Review/WPXI-TV showed Altmire with a mere 4-point lead over Critz.

Another sign the race has closed came when both candidates emptied their campaign bank accounts in the final two weeks. Critz even dipped into his own wallet to fund the final days by loaning his campaign $100,000.

Altmire will benefit if the snow falls hard on Critz’s base in Johnstown — a scenario local meteorologists predicted over the weekend. But as of Monday afternoon, a Critz spokesman said the snow wasn’t sticking — yet.

“It looks like we dodged a bullet and the weather isn’t going to be much of a factor at all,” Critz staffer Mike Mikus said.

If Altmire and Holden both lose today, they will join the growing number of Blue Dog Democrats who won’t return to Congress next year.

Holden is seeking re-election in a district that’s almost 80 percent new turf for the 10-term incumbent. As a result, Cartwright has gotten a lot of traction running to Holden’s political left, aided by outside Democratic groups.

“It’s really tough for Holden because he really got the short end of the redistricting deal because so much of the district is new to him,” Ceisler said. “It’s almost as if he’s not the incumbent.”

Holden boasts the backing of several well-known Democrats, including Sen. Bob Casey and, most recently, former Gov. Ed Rendell. He’s also raised significant money — more than $70,000 — from his Congressional colleagues.

Despite this cash infusion, the Congressman has been outspent in the district. Cartwright has put almost $400,000 of his own money into his campaign, plus outside groups such as the League of Conservation Voters and a Texas-based super PAC kicked in a combined $300,000 to attack Holden.

Meanwhile, Republicans are monitoring three primaries: the race for retiring Rep. Todd Platts’ south-central seat, Rep. Tim Murphy’s intraparty challenge in the southwestern corner of the state and the wide-open race to select a nominee to face Casey.

“The big one, obviously, is the U.S. Senate race,” Pennsylvania Republican strategist Charlie Gerow said. “I think that’s boiled down to a three-horse contest between the two millionaires at polar sides of the state and Sam Rohrer in the middle.”

Former coal company executive Tom Smith, who has spent millions blanketing TV airwaves, has the edge in the Senate primary. The winner faces an uphill battle against Casey this fall.

Smith has spent more than $3.7 million on the race and loaned his campaign almost $5 million in personal funds.

But while Smith has the financial edge, businessman Steven Welch has the support of top GOP officials in the state, including Gov. Tom Corbett. Welch won the state party’s endorsement earlier this year, too.

Rohrer, a former state Representative, has support from many grass-roots activists. But he has only raised a fraction of the money that the other two candidates have.

In southwestern Pennsylvania, Murphy is on track to win his primary easily. Conservative activists were initially excited about his opponent, former U.S. Senate aide Evan Feinberg, but he could not raise enough money to give Murphy a formidable challenge.

“I think Tim Murphy will not only survive but win handily,” Gerow said. “The candidate they ran against him was apparently a nice guy but just moved back into the district.”

Finally, in south-central Pennsylvania, the GOP primary to succeed Platts has boiled down to two frontrunners: state Rep. Scott Perry and York County Commissioner Chris Reilly.

Sen. Pat Toomey (R-Pa.) supported and campaigned for Reilly frequently during the campaign. Reilly had a financial advantage, too, but Perry had more support from other Republicans — including Corbett.

The winner of the GOP primary is expected to become the next Member of Congress. The redrawn 4th district is a safe GOP seat.

The polls close at 8 p.m. today, according to a spokesman from the elections department at the Pennsylvania Department of State.