An ambitious project launched this year to enable the Republican National Committee and GOP-allied outside groups to share information from the field amounts to illegal coordination, a Democratic legal watchdog group alleged in a complaint filed Tuesday with the Federal Election Commission.

The RNC emphatically rejected the charge, calling it politically motivated.

At issue is the role played by Data Trust, a private company that has an exclusive list-exchange agreement with the RNC. Through an application interface created by Data Trust, the party and outside groups that are its clients can access and update profiles of individual voters in real time.

American Democracy Legal Fund, a new group helmed by veteran Democratic operative Brad Woodhouse, said that such a flow of data back and forth is not permitted under federal election rules banning coordination between parties and outside groups.

“What they’re doing here looks to be such a violation and flouting of the law, it’s just not to be believed,” said Woodhouse, who also runs the Democratic opposition research super PAC American Bridge, adding: “Our attorneys couldn’t figure out how anyone on our side could conceive of doing anything like this.”

RNC officials said the data-sharing was thoroughly vetted by lawyers and similar to efforts on the left.

"It’s not surprising a liberal Democrat hack would file a baseless complaint 21 days before midterm elections that poll after poll shows the Democrats are losing," said party spokeswoman Kirsten Kukowski. "Clearly we’re doing something right with data and technology if the Democrats are spending their time fighting us."

Data Trust did not respond to a request for comment.

The complaint spotlights how outside groups on both sides of the aisle have pushed the boundaries of coordination in this year’s election.

It is common for parties and outside groups to exchange voter lists. But Democratic party committees and allied interest groups do not to conduct such exchanges close to an election, according to people familiar with the transactions. That’s because conveying non-public material related to a campaign’s activities through a common vendor could violate coordination rules.

So operatives on the left were puzzled when Data Trust, which is run by a former top adviser to House Speaker John Boehner, announced this summer that it had created an application interface that would give its clients “real time, direct access” to its voter file. That allows the RNC and outside groups such as American Crossroads, an early backer of the project, to share information from the field.

The voter file was further enriched in August, when Data Trust struck a partnership with i360, a data management company that works with the advocacy group Americans for Prosperity and about a dozen other groups in a political network backed by Charles and David Koch and other conservative donors.

That means that information about voters gathered by AFP field staff could filter back to GOP campaigns.

“By examining party and candidate data immediately and day to day, the outside groups that are required to operate independently can easily determine who the party and candidates are targeting, which areas they are focusing their efforts, where their field programs have holes and need additional support, and the equivalent of insider polling – essentially the entire private field strategy of a campaign or party operation,” according to the complaint filed by American Democracy Legal Fund. The complaint was lodged against the RNC, Data Trust, i360, Crossroads and AFP.

AFP spokesman Levi Russell called the allegations “a politically motivated attack without merit.”

“All anyone really needs to know is that this complaint comes from a front group linked to the Democracy Alliance, Democrat operative David Brock, and former DSCC spokesperson Brad Woodhouse,” Russell said in a statement. “We fully expect this complaint will be dismissed, as all frivolous complaints should be.”

It’s unlikely that a polarized FEC -- which has deadlocked on major enforcement cases in recent years -- will take up the issue in the remaining weeks before Election Day. But Woodhouse said he is hopeful the commission “will take this seriously and address this well before this activity is allowed to continue in an accelerated way before the next one.”