In theory, reform advocates on Capitol Hill should have an easy time rounding up support for their bill responding to the Supreme Court's controversial ruling to free up corporate political spending.

After all, polls show that voters of all stripes deplore the court's Citizens United v. Federal Election Commission decision, which threw out a decades-old ban on direct campaign expenditures by corporations and (by extension) unions. One ABC/Washington Post poll found that 8 in 10 respondents oppose the ruling.

In practice, though, Sen. Charles Schumer, D-N.Y., and Rep. Chris Van Hollen, D-Md., have hit resistance on multiple fronts as they've toiled to craft post-Citizens United legislation. The bill's backers anticipate intense opposition when it is finally introduced as early as this week, and not just from conservatives.

The bill's authors argue that its bedrock is disclosure, which the Supreme Court defended in

Unions, civil rights organizations and progressive 501(c)4 advocacy groups have all quietly voiced concerns during the drafting process, and some may balk when details of the Schumer-Van Hollen plan emerge. Congressional Republicans, including those who supported the McCain-Feingold bill that banned soft money in 2002, have largely failed to come on board. The resulting delay may jeopardize the bill's final passage.

A big problem for Schumer and Van Hollen is that it's a lot harder than it looks to clamp down on big-spending corporate interests without sweeping up politically active progressive groups friendly to Democrats, including unions. It's the same problem President Obama faced last year, when he set out to bar lobbyists from his administration but ruffled the feathers of left-leaning nonprofit activists who felt shut out.

"It's a really hard piece of legislation to [write] to be able to get at the 'bad' influence and not the 'good,' however that's defined," said Abby Levine, deputy director of advocacy programs at the Alliance for Justice, a progressive umbrella group. Alliance for Justice is one of several liberal 501(c)4 groups whose organizers fret that the Schumer-Van Hollen bill may inadvertently hamstring legitimate issue advocacy, Levine said.

Often lost in the debate over Citizens United is that the ruling opens up campaign spending not just for big, for-profit corporations but for incorporated organizations of all kinds, from unions to trade associations and nonprofit advocacy groups. Likewise, the Schumer-Van Hollen bill would impose complicated new disclaimer and disclosure requirements across the board, not just on corporate players but on a broad universe of politically active groups, including nonprofits subject to nominal disclosure now.

And some progressive activists are eager to exploit their new freedoms under Citizens United. The AFL-CIO is poised to spend tens of millions in half a dozen key congressional elections in a bid to block a Republican takeover of Congress, the Wall Street Journal reported last month. The Alliance for Justice has urged nonprofits to "take advantage of" the Citizens United ruling, stating in a Web posting: "More than ever, nonprofit corporations can and should actively participate in elections."

Now, politically active progressives want to ensure that the Schumer-Van Hollen bill doesn't get in their way. The bill is expected to closely track a summary that its authors released in February. Among other provisions, it would:

• Ban independent campaign spending by corporations that have 20 percent or more foreign ownership, and by government contractors and recipients of bailout money under the Troubled Asset Relief Program.

• Require sponsors of political ads to run disclaimers, either by the corporate CEO or by the top donor or contributors who underwrote the ad.

• Impose elaborate new disclosure requirements on politically active groups. These could include requiring politically active corporations or groups to set up "political broadcast spending" accounts that would disclose five-figure donations and transfers to the Federal Election Commission. They could also include disclosures to shareholders through Securities and Exchange Commission filings.

• Allow candidates facing unregulated corporate independent expenditures to buy affordable broadcast ads using the so-called lowest unit rate.

• Tighten up rules aimed at blocking coordination between those making independent political expenditures and candidates.

The disclosure and coordination rules, in particular, concern the Alliance for Justice, said Levine. Along with the Sierra Club and the AFL-CIO, the Alliance has already petitioned the FEC, which is writing its own coordination regulations, not to define "coordination" too broadly. If coordination and disclosure requirements aren't narrow enough, said Levine, they could chill both advocacy and donations to nonprofits.

Alliance officials have been meeting with congressional aides in a bid to write legislation that responds to Citizens United "in a way that does not limit constitutionally protected and very useful and needed advocacy," she said.

The bill's authors argue that its bedrock is disclosure, which the Supreme Court defended in Citizens United, and which Republicans have historically endorsed. "Our Republican colleagues have said they support disclosure, and that is the heart of the bill," Van Hollen recently told public radio host Patt Morrison. The post-Citizens United fixes, he added, "should be a nonpartisan issue."

But for all its potential appeal, the Schumer-Van Hollen bill is already walking a political tightrope. Between conservatives poised to challenge its constitutionality and liberals nervous about new coordination and disclosure rules, the bill is bound to stir up quite a fight.

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