CIRCULATING MEMO: SUPPORT FOR REFORM ON THE RISE…. For all the talk that public opinion on health care reform simply cannot improve, public opinion on health care reform is improving.

We talked yesterday about the general trend lines in national polls, which show support increasing, and opposition decreasing, over the last couple of months. A memo that’s circulating on the Hill today is making a related case directly to lawmakers.

A new polling memo from Joel Benenson, the White House’s pollster of choice, argues that support for President Barack Obama’s health care plan has been building in the wake of his State of the Union speech in late January.

Since February 1, according to data compiled by Benenson, 44 percent of those tested in national surveys support the bill while 45 percent oppose it — a sea change from the 38 percent favor/52 percent oppose average of polls conducted in the three months prior.

That movement, argues Benenson, is born out of a continued desire from the American people for Congress to pass some sort of health care reform and broad popularity of some of the major measures contained in the bill.

Public attitudes can shift for a wide variety of reasons, some of which may or may not make sense. Maybe the polls are shifting because more Americans are learning what’s actually in the reform package. Perhaps folks are seeing their own premiums go up, and are reconsidering their earlier skepticism about the Democratic plan. Maybe the recent summit and presidential appearances are having an effect. Perhaps folks have been turned off by absurd Republican tactics, and decided to give the plan another look. Speculating about the rationale for poll shifts is inherently tricky.

But the bottom line remains the same: the polls are shifting, and they’re moving in a helpful direction for reform advocates.

For congressional Dems, this should help stiffen spines a bit, and undermine the assumption among Republicans that reform is an unpopular mess.

To reiterate a point from yesterday, if Democrats wanted to they could start pushing the idea that the tide is turning, momentum is starting to build, and it’s time to start pushing a “comeback” narrative.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.