Steve Rosenthal has long worked the Democratic grass roots and helped mobilize Democratic voters. Now he is trying to keep Democratic Congressmen in line.

Earlier this year, Rosenthal, along with other union stalwarts and some big names from the net-roots community, has formed a political action committee called Working for Us and a nonprofit advocacy group called They Work for Us. They have begun only recently to talk about their goals and tactics.

“The mission is we want to hold Democrats’ feet to the fire on these really core issues,” said Lisa Prosienski, the executive director of They Work for Us. It boils down to ensuring that Democratic lawmakers are economic populists, she said.

The organization’s nonprofit arm got off to an early start, running what Prosienski described as a “mini-campaign” in January. They Work for Us ran radio ads and contacted voters urging them to get in touch with Sen. Max Baucus (D-Mont.) about fast-track authority on trade agreements.

Baucus, as chairman of the Senate Finance Committee, will play a lead role in whether presidents can fast-track trade agreements. That means Congress can only vote for or against the trade deal without any amendments.

They Work for Us encouraged Baucus to meet with union leaders, which he did, said Rosenthal, a former political director of the AFL-CIO.

Carol Guthrie, Baucus’ committee spokeswoman, said that Baucus supports fast-track authority, with caveats.

“The chairman’s position is that fast-track authority needs to be renewed with smart changes that improve environmental and labor standards, and that make it a more powerful job-creating tool for American workers and businesses,” Guthrie said.

Rosenthal said the PAC is just getting off the ground. According to its year-end report, the most recent available with the Federal Election Commission because the PAC only plans to file campaign reports semi-annually in 2007, They Work for Us had about $10,000 in the bank.

The issue advocacy arm has a substantial budget of $3.5 million, Rosenthal said. The two entities have separate boards, with only Rosenthal serving on both.

The PAC must abide by FEC limits and report all its activities. There are no caps on the size of donations They Work for Us can accept. It also does not have to reveal its contributors.

Rosenthal said the Club for Growth, a financial powerhouse that has made its reputation — and enemies — by spending lavishly in GOP primaries, is something of a model for his group.

“We’ve been talking about the need of this kind of organization on the left,” he said.

The Club for Growth earned the enmity of the National Republican Congressional Committee and the National Republican Senatorial Committee last year by expending a lot of energy on unseating then-Sen. Lincoln Chafee (R-R.I.) and then-Rep. Joe Schwarz (R-Mich.) instead of working to shore up the GOP’s fragile Congressional majorities.

“The difference is the club didn’t give a damn about the Republican majority and we do give a damn about keeping the Democratic majority,” Rosenthal said.

The Democratic Congressional Campaign Committee likely will watch the group carefully.

“We are focused on expanding our majority,” said DCCC spokesman Doug Thornell. “We hope others will do the same.”

While Rosenthal says Working for Us will not shy away from primaries, he said the group will not target vulnerable Democrats.

“Our goal is not to do anything to jeopardize the Democratic majority,” he said. “Many of the same people behind our organization are the ones who worked the hardest for Democrats” in the past, he added.

Rosenthal, who steered the massive Democratic get-out-the-vote operation in 2004 under the liberal 527 group America Coming Together, now focuses on his consulting business, The Organizing Group, and on They Work for Us.

He is joined on the board by Tyrone Freeman, general president of Service Employees International Union Local 434B; Thomas Matzzie, Washington director of MoveOn.org Political Action; and Michael Monroe, administrator for government affairs of International Union of Painters and Allied Trades.

Rosenthal declined to say which Democrats might be targeted but he often has used Rep. Henry Cuellar (D-Texas) as a prime example of the type of Democrat who should be careful.

Democrats in safe districts should vote like Democrats, he said.

Cuellar received a 48 percent conservative ranking in National Journal’s most recent analysis of House votes.

That means that in the 109th Congress, he voted more conservatively on key economic votes than 48 percent of his fellow House members.

Cuellar also earned the endorsement of the Club for Growth last year — the first Democrat ever to get the seal of approval from the pro-business, anti-tax group.

Rep. Dan Boren (D-Okla.) received the highest conservative score of any Democrat on economic issues — 52 percent — but Rosenthal said the group is more understanding of Members in tough districts.

Boren’s 2nd district in the Sooner State gave President Bush 59 percent of the vote in 2004. Cuellar’s district, after Republicans pushed through a new map mid-decade, is now solidly Democratic, he said.

Cuellar, Reps. Ellen Tauscher (D-Calif.) and Albert Wynn (D-Md.). “are good examples of the type of Member … we are tracking — their voting records are more conservative than their districts, and at times each of them has actively stepped away from the Democratic caucus, to the detriment of constituents in their districts,” according to the PAC’s Web site.

Donna Edwards, who challenged Wynn in last year’s Democratic primary and is likely to do so again in 2008, is on the board of They Work for Us.

Tauscher has earned the ire of liberal activists of late in her role as head of the New Democrat Coalition.

However, she is way down National Journal’s list, earning a paltry 18 percent on conservative issues.

Much higher up is Rep. William Jefferson (D-La.) who clocks in at 43 percent despite representing a district that gave Sen. John Kerry (D-Mass.) 75 percent of the presidential vote in 2004. Rep. Silvestre Reyes (D-Texas) earned a 40 percent even though he sits in a 56 percent Kerry district.

“Last year, 73 Democratic House members voted for the bankruptcy reform bill, which favored credit card companies and banking interests over consumers,” the PAC’s Web site continues. “There is especially no excuse for those Members who have strong Democratic districts, but still vote against the interests of their working-class constituents — those are the worst offenders.”

Rosenthal said his groups ultimately could be mobilized in 15 districts. By summer he hopes to be engaged in three or four states.

No one has been approached to run against a sitting Democratic Member in a primary yet, but Rosenthal is meeting with a potential candidate — whom he did not name — next month.

Rosenthal said Working for Us may even step outside Democratic primaries.

In some overwhelmingly Republican districts with very conservative Members, the PAC might try to recruit and support a moderate Republican, he said.

“We’re looking for any and all allies,” Rosenthal said.