What Democrats in Congress will do if they're in power after midterms

In more than a dozen interviews, CNN has learned that Democrats on virtually every committee in the House of Representatives are carefully positioning themselves to be ready in the event that they find themselves in the majority after the midterms.

But, sources say, it is a delicate balance. After nearly a decade in the minority and two years having limited power to pursue oversight in the Trump administration, Democrats need to be prepared. But leaders are encouraging members to use restraint and be mindful of the fact they haven't won the majority yet and pursuing oversight too aggressively could set the party back in 2020.

"I have said 'let's not be counting chickens yet,'" Arizona Rep. Raul Grijalva, the top Democrat of the House Natural Resources Committee, told CNN.

Staff level discussions are well underway about how Democratic-led committees would divide the work and tackle whole entire controversies that have roiled the Trump administration from questions about whether the President's family has profited from Trump's time in the White House to ethics questions surrounding Cabinet secretaries to the very policies like family separations along the southern border that have made headlines.

One Democratic leadership aide told CNN that at this point, the key role of leaders is to help each of the committees coordinate their efforts so that investigations are targeted and yield results, not just rhetoric.

One person familiar with ongoing discussions said Democrats are well aware that attacking every corner of controversy in the Trump administration could backfire politically just before a presidential election and put Democrats on the wrong track to keep the majority. Already, Republicans are using the threat of Democratic investigations to get out their base.

"On a political level, it's enormously helpful. I think a lot of our candidates are talking about if the Dems get the House, they will try and impeach (Supreme Court Justice Brett) Kavanaugh, they'll try and impeach the President," Sen. John Thune, a member of GOP leadership, told CNN. "I think when people see the specter of a Nancy Pelosi led House, a Jerry Nadler-led Judiciary Committee and Maxine Waters on Banking, I think all of those possibilities are very reinforcing to our voters."

The pursuit of Trump's tax returns

A top target for Democrats remains Trump's personal tax returns, an ask that Democratic Leader Nancy Pelosi told the the San Francisco Chronicle's editorial board last week is "one of the first things we'd do."

Trump defied norms when he refused to release his returns on the campaign trail.

But, aides expect a protracted legal battle in the fight for the returns, one that could very easily escalate from a potential House Ways and Means Chairman Richard Neal, a Massachusetts Democrat, asking for the returns in the early days of a Democratic House to Treasury Secretary Steve Mnuchin denying the request and the parties going to court for months.

Neal, seen more within the caucus as an institutionalist than a liberal agitator, told CNN on Friday that he would hope the President would hand his returns over voluntarily.

"I think we would all be comfortable if this was done on a voluntary basis," Neal said, adding, "If they would resist the overture then I think you could probably see a long and grinding court case."

Behind the scenes, there has been some reluctance to even pursue them and aides are trying to set expectations within the caucus about what it will mean for the party if it makes the tax returns a cornerstone of its investigative pursuit against Trump. It's an unprecedented move that could be seen as an all-out political war against the President. There are also still questions about the scope of the returns that Democrats should seek. Should it just be personal returns? How many years? What about Trump's corporate returns?

There is also some discussion about whether there could be a parallel effort where Democrats introduce legislation to force all future presidential nominees to release their personal tax returns, a move that would be nothing more than a message exercise if Republicans remain in control in the Senate.

Russia

After Republicans on the House Intelligence Committee ended their Russia investigation in March, the committee's Democrats started interviewing witnesses on their own to continue the probe.

They're poised to ramp up in a major way should Democrats take the majority.

The panel's ranking Democrat, Rep. Adam Schiff, laid out a road map in March for where he would take the investigation with the power to call witnesses and issue subpoenas. The 21-page document included eight areas he wants to investigate, more than 30 officials that Republicans did not interview, document requests to a host of companies and subpoenas to numerous senior Trump officials, including Donald Trump Jr., Jared Kushner and Steve Bannon.

If he becomes chairman of the Intelligence Committee in January, Schiff is likely to pick up on the subpoenas and interview requests, which could set off a protracted battle with the White House.

Schiff wrote an op-ed in The Washington Post published online Friday making the case that a Democratic House would provide a check on Trump through oversight, detailing his plans for his panel.

"In the Intelligence Committee, we will assess the work we have accomplished despite the Republican efforts at obstruction, along with what the Senate and special counsel Robert S. Mueller III have examined, and determine what else needs a full accounting," Schiff wrote. "There are serious and credible allegations the Russians may possess financial leverage over the president, including perhaps the laundering of Russian money through his businesses. It would be negligent to our national security not to find out."

But he's not the only chairman who's likely to probe matters involving Russia. Rep. Jerry Nadler, the top Democrat on the House Judiciary Committee, has pressed Judiciary Chairman Bob Goodlatte, a Virginia Republican, to investigate possible Russian collusion, among other topics, rather than the GOP probe conducted into the FBI's handling of the Russia investigation. If Democrats have the majority, Nadler is likely to probe Russian meddling as part of a lengthy list of issues, from Michael Cohen's payments to women to potential obstruction of justice to Trump's finances.

Nadler, whose committee would be in charge of a potential impeachment process, has been careful to say he's not planning to move forward on impeachment yet. But all of the issues he's signaled he wants to investigate would lay the groundwork for such a case should Democrats decide to press forward on it.

Beyond Trump's taxes and Russia

Taxes and Russia are just the beginning.

The House Oversight and Government Reform Committee -- one of the most equipped committees to handle investigations into Trump -- would become the center of gravity for investigations just like it was during the Bush administration in the mid-2000s.

Already, ranking member Elijah Cummings, a Maryland Democrat, has pursued information related to any potential violations of the Emoluments clause, questions about how the administration has handled security clearances, and questions about Trump's own Washington hotel, setting out a road map to what his priorities would be if he wins the gavel in November.

"If I am lucky enough to become Chairman of the Committee, I see my role as having two lanes," Cummings said in a statement. "I want to look at all the things the President has done that go against the mandates of our founding fathers in the Constitution. In the second lane, we need to look at things that effect people on a day to day basis and address the things that we're fighting for, like access to healthcare, the right to vote, the skyrocketing cost of prescription drugs, reforming the postal system, and questions about the Census."

Nadler has also said he wants more information on Kavanaugh who was accused in the 11th hour of his confirmation process of sexually assaulting Christine Blasey Ford when they were both teenagers. Kavanaugh vehemently denied the allegations and after the FBI reopened its background investigation into him, Kavanaugh was confirmed to the Supreme Court.

"It is not something we are eager to do," Nadler told The New York Times earlier this month. "But the Senate having failed to do its proper constitutionally mandated job of advise and consent, we are going to have to do something to provide a check and balance, to protect the rule of law and to protect the legitimacy of one of our most important institutions."

That's just the beginning. While Democratic aides stressed to CNN that leadership and ranking members had made no final decisions about what committees would investigate, they have started laying out a menu of options. The guiding principle, according to people familiar with the discussions, is to not only just investigate Trump, but to also investigate the ways in which the administration is chipping away at key Democratic priorities like the Affordable Care Act or environmental protections.

The House Energy and Commerce Committee for example could look into ways the Department of Health and Human Services is using power at the agency to roll back protections for people with pre-existing conditions. The House's Education and Workforce Committee might pursue investigations into how Education Secretary Betsy DeVos is implementing the Every Student Succeeds Act or whether any ties to for-profit colleges are influencing the direction of the agency. As a result of Democratic control, Cabinet secretaries may be spending a lot more time testifying before the committees of jurisdiction.

"You can expect more invitations," Grijalva said when asked if Interior Secretary Ryan Zinke would be spending more time on Capitol Hill giving testimony.

A key question that is still ongoing on Capitol Hill is whether Democrats would look to relitigate controversies within some of the agencies that have already occurred that includes ongoing investigations ongoing into Zinke. Grijalva told CNN his strategy would be to let the inspector general's office do the work rather than run parallel investigations.

In addition to wanting to carefully pick their targets, aides warn it could take some time to fully kick into gear on some of the policy-focused committees aren't equipped with robust investigative teams.