It's 2014, and we're all anti-Obamacare now - at least a little. Even party-sanctioned Democratic Super PACs are now defending their members with ads that showcase the sincerity of their frustration with Obamacare's rollout.

And late last week, incumbent Senate Democrats lined up around the block to sign an anti-Obamacare letter. Well, okay - it wasn't really “anti-Obamacare,” but we would have called it that if it had been written in 2010, or even just a few months ago. Now, even liberal Sen. Chuck Schumer, D-N.Y., can't keep his pen off it. Among the 19 Democratic signers are vulnerable Democrats defending Senate seats this year - Mark Pryor, D-Ark., Mark Begich, D-Alaska, Mark Udall, D-Colo., Kay Hagan, D-N.C., and Mary Landrieu, D-La.

The senators' letter asks President Obama's Medicare administrator to avoid applying cuts to the same semi-private Medicare Advantage program that they all voted to cut in 2009 when they all voted for Obamacare. Back then, their party leaders parried criticism by condemning Medicare Advantage as an ineffective program. In contrast, the new letter expresses concern for the 15 million people enrolled in Medicare Advantage, noting that its plans “offer more flexible services and benefits than traditional Medicare.”

The letter concludes, “We urge you to maintain payment levels that will allow MA beneficiaries to be protected from disruptive changes in 2015.” As it happens, people within the program have already seen their doctor access reduced -- another politically explosive upshot of Obamacare that goes beyond its website, its insurance cancellations, and its higher premiums and deductibles.

In 2010, Republicans made much of the diversion of $716 billion from Medicare ($200 billion of that from Medicare Advantage) to fund Obamacare. It had been intended as a budget gimmick to make the health care law deficit-neutral at the time of its passage. But it was a grave political miscalculation that could have long-lasting effects.

All policy questions aside, by gutting an old-age entitlement program, Democrats destroyed one of their best evergreen election-year pitches to older voters - that Republicans just want to gut old-age entitlement programs.

In October 2012, the Kaiser Family Foundation released a study tracking polling on Medicare going back to the early 1990s. Democrats have traditionally enjoyed a large double-digit advantage over Republicans on the issue, especially among senior citizens. For example, on the issue of Medicare, Al Gore enjoyed a 17-point advantage with seniors over George W. Bush in 2000. Democrats in Congress have traditionally enjoyed a similar advantage over their Republican counterparts - at one point during the Bush era it was as high as 26 points.

But when Obamacare was debated and passed, the Democrats' edge with seniors on Medicare quickly vanished. The GOP took a narrow two-point average advantage in the five polls that asked between 2009 and 2010. And although Democrats later reclaimed a small edge, the 2012 election was the first since at least 1996 (and possibly ever) in which senior citizens trusted a Republican nominee over a Democrat on the issue of Medicare. Mitt Romney enjoyed an average five-point advantage among seniors in 17 polls that asked about Medicare in 2012.

That Democrats are on the defensive and signing a letter that until recently only Republicans would have signed suggests we may already be living a post-Mediscare era. There was a time when even the hint of reform could be snuffed out by attack ads and robocalls and mailers about scary Republicans taking away your Medicare. For sitting Democratic incumbents last elected in 2008 — such as all five senators listed above — and for the super PACs aiming to help them out, the electoral landscape has changed. They go to battle this year lacking a weapon they had just six years ago.

For that, they have their own votes for Obamacare to thank.

DAVID FREDDOSO, a Washington Examiner columnist, is the former Editorial Page Editor for the Examiner and the New York Times-bestselling author of "Spin Masters: How the Media Ignored the Real News and Helped Re-elect Barack Obama." He has also written two other books, "The Case Against Barack Obama" (2008) and "Gangster Government" (2011).