While admitting they’ll lose seats in November, Democrats hope to limit the losses by pointing to a long list of legislative achievements, an improving economy and, especially, consistent Republican naysaying.

[IMGCAP(1)]They also hope that the tea party movement’s shoving Republicans to the right and out of mainstream appeal to independents will counterbalance the movement’s political energy.

And, according to Rep. Chris Van Hollen (Md.), chairman of the Democratic Congressional Campaign Committee, the Republican “playbook” for the fall campaign — “demonizing” President Barack Obama and Speaker Nancy Pelosi (D-Calif.) — did not work last week in Pennsylvania and can be countered elsewhere.

The big drags on Democratic prospects, of course, are continued high unemployment, public dissatisfaction with the direction of the country and with Congress’ performance, Obama’s sub-50-percent approval rating, and previous Democratic success.

As Van Hollen noted in a breakfast session with reporters, Democrats have picked up 55 House seats in the last two elections, winning about all the swing districts in the nation.

Historically, the party in control of the White House almost always loses ground in midterm elections. The average since 1954 (excluding the post-9/11 election in 2002) is 17 House seats, but it’s 30 when the president’s approval rating is below 50 percent.

Without discussing numbers, Van Hollen acknowledged that “we are in a challenging political environment. … Democrats have an uphill battle.” A top White House adviser told me he thinks Democrats would be “lucky” to lose only 30 seats.

And yet, there are countervailing forces. Even though the public doubts that the Democrats’ $862 billion stimulus package helped the jobs picture, the Congressional Budget Office just reported that it created 1.2 million to 2.8 million jobs and kept the unemployment rate — now 9.9 percent — from reaching 11.5 percent.

As the campaign goes on, an Obama aide told me, the White House message will be that “faced with the deepest recession and the most significant economic crisis since the Great Depression, the president moved aggressively on a plan to stabilize, rebuild and grow the economy.

“He took the tough, sometimes unpopular actions that were required to pull the country back from the brink … and the president’s plan is beginning to restore economic growth, create jobs and expand opportunity.”

Indeed, that’s been the Obama theme in a series of speeches he’s delivered recently at sites in Youngstown, Ohio, Buffalo, N.Y., and Fremont, Calif., where stimulus money created private-sector jobs.

To Van Hollen’s obvious delight, Obama has taken to using a DCCC theme against Republicans: “They’ve done their best to gum up the works, to make things look broken, to say no to every single thing,” he said at a DCCC dinner in New York.

“Their basic attitude has been: ‘If the Democrats win, we lose.’ So after they drove the car into the ditch, made it as difficult as possible for us to pull it back, now they want the keys back.

“No! You can’t drive! We don’t want to have to go back into the ditch. We just got the car out!”

Polls show that voters still blame George W. Bush more than Obama for the recession and federal deficits. Van Hollen said Democrats will argue that if they take over the House, Republicans will continue those policies.

So, Van Hollen said, Democrats will try to shift voters’ attention from mere dissatisfaction with incumbents toward the philosophy and policies of Republicans.

“This is not just a referendum on Washington, but in every case, in every race around the country, you’re going to have a choice between two different candidates and two different visions of the future, especially on big issues of economic policy,” Van Hollen said.

That worked, he said, to elect Rep. Mark Critz (D) in western Pennsylvania last week in a race where Republicans spent more than $1 million.

The defeat led the Wall Street Journal to editorialize, “Republicans who were already planning their Nancy Pelosi retirement party galas for November may want to cancel the caterer.

“The GOP lost the most important election held [May 18], and if it fails to learn from the experience, the party may lose in the autumn, too.”

Van Hollen thinks that his side will be helped, too, by the defeat of mainstream GOP candidates by tea party candidates in Illinois, Kentucky and Idaho, and rightward moves by other Republicans to appeal to activists.

What the Democrats have not done so far is to lay out a list of all the achievements of their and Obama’s tenure.

I asked the White House for its list, and it’s actually remarkable, although Republicans are right to say that it will expand deficits and deepen the nation’s debt.

The list includes, besides the original stimulus package and subsequent jobs bills, comprehensive health care reform (passed after it was given up for dead) and student loan reform that doubles funding for Pell Grants and caps yearly loan costs.

While the main provisions of health care reform — coverage of 30 million uninsured — will not take effect until 2013, first (election) year benefits include elimination of pre-existing insurance exclusions for children and coverage for dependents up to age 26.

The stimulus package included provisions both to help states keep teachers and police employed amid budget crunches last year, and to launch the administration’s exemplary “race to the top” education reform program.

About 300,000 teachers may lose their jobs this year if a $23 billion amendment is not passed, undermining prospects for reform. Democrats could well use against Republicans a GOP Senate leader’s comment that he’d oppose saving teachers’ jobs even if paid for by offsetting cuts because “I don’t believe that’s an emergency in any way, shape or form.”

As the White House points out, Democrats also have passed legislation preventing tobacco companies from marketing to children, a credit card rights act protecting consumers from surprise interest changes and major increases in military pay and veterans services.

Financial services reform has passed both chambers and is on its way to enactment. When that’s done, according to the New York Times’ David Leonhardt, “Congress and the White House [will] have completed 16 months of activity that rival any other since the New Deal in scope or ambition.

“Like the Reagan Revolution or Lyndon Johnson’s Great Society, the new progressive period has the makings of a generational shift in how Washington operates.”

So Democrats have something — actually, a lot — to sell this November. And Republicans, so far, have next to nothing that anybody knows about.

And, to underscore the point, the latest NBC/Wall Street Journal poll shows that while only 35 percent of voters have a favorable impression of Congressional Democrats, only 20 percent think well of Republicans.