Republicans are citing their momentum in two special elections being held Tuesday as evidence that the national political environment has shifted against Democrats and President Obama.

Assemblyman David Weprin is in a surprisingly close race for a House seat in New York. (Ken Goldfield/AP Photo)

And they are both right. Kind of.

The two competing storylines coming out of very different special elections just 130 days apart shows just how fickle American voters are right now.

They also demonstrate that any Republican momentum should be seen as momentary, and that the electorate four months hence could just as well revert back to punishing Republicans.

Meanwhile, all eyes Tuesday will be on whether the GOP can truly steal the seat of former congressman Anthony Weiner (D-N.Y.) and keep that of now-Sen. Dean Heller (R-Nev.).

Here’s how things now stand:

Four months ago, Democrats successfully turned the GOP’s Medicare proposal into a real clunker, defining the GOP nominee in New York’s 26th district early and winning a long-held Republican district in the process.

Today, the political environment is almost completely reversed, with Obama’s problems endangering a New York City district in which Democrats hold a three-to-one registration advantage and a Nevada seat that nearly went for the president in the 2008 election.

These are the competing storylines, and both the Republican and Democratic versions have a lot of truth to them, despite their close proximity in time.

The shift is notable, but it’s not unheard-of. Democrat point out that they held a very conservative Pennsylvania House district less than six months before Republicans cleaned their clocks in the 2010 general election.

It’s important to remember that local and national factors tend to skew a special election more than a regular race. Low turnout and an increased focus on a special House election by the national parties mean pretty much anything can – and has - happened in recent years in these races.

As we wrote back in May, these races are hypersensitive to the national environment and tend to show bigger shifts than would occur in a normal election. These specific House contests are also occurring in unique House districts, with the heavily Jewish New York City 9th district being a great example of that.

(Democrats are already blaming New York Democratic nominee David Weprin’s vote for same-sex marriage from when he was in the state Assembly for alienating Jewish voters.)

The current developments still have to be troubling for Democrats, said Stu Rothenberg of the Rothenberg Political Report.

“But a lot can change in the next 14 months, so it would be foolish to read too much into a couple of special elections,” Rothenberg said.

While special elections often aren’t great predictors of what lies ahead, that goes double in the current environment.

Congress’s record low approval ratings and the country’s continued economic problems have led the American people to look for someone to blame. For a time, the Democrats had some success in shifting that blame to Republicans; now, it’s more squarely on the president’s shoulders.

And next week or next month, things could just as easily shift right back.

“What Republicans will take out of this is that Democrats are in a lot of trouble, and they’re right,” said former Rep. Tom Davis (R-Va.). “However, the same could apply to a Republican seat in this environment.”

Republicans, for their part, say they won’t overplay their hand if they win.

They point out that Democrats in May touted their win in New York’s 24th district by saying that they were now able to win the two dozen seats they needed to recapture the House majority. Four months later, with a potential loss in heavily Democratic New York City’s 9th district, that doesn’t appear nearly as likely.

“Democrats said this put the House in play for them, and look at where we are today,” said a GOP strategist granted anonymity to discuss the situation candidly. “This may tell you some things about the coming cycle, but it goes to show you that the political environment can change.”

More than anything, these special elections are a good measure of what the current issue matrix looks like.

So, while we knew Rep. Paul Ryan’s (R-Wis.) Medicare plan (which would turn the program into a voucher system) was working for Democrats in May, it doesn’t appear that it has continued to be a liability for Republicans – at least not when matched with the country’s economic problems.

“In a post-debt ceiling, post-downgrade environment, independents see the Ryan plan as more of a distant memory than an immediate threat,” said David Wasserman of the Cook Political Report.

Things are still changing very fast, though, and with the debt reduction “supercommittee” starting to meet, entitlements like Medicare could again be a big part of the debate.

And when it comes to the current state of politics, we’re not putting anything past American voters. Perhaps more than ever, they seem very happy to change their minds in very short order.

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