The fishing expeditions planned by House Democrats won’t be confined to Lake IRS. The Washington Post reported last night that Democrats have attempted to bypass the White House’s legal defense against subpoenas on Donald Trump’s financial records by going after the records at the financial institutions instead. Capital One told House Democrats last month that a subpoena will be required, and that’s not going to be much of a problem for the three committee chairs involved:

Three powerful House Democrats asked Capital One Financial last month for financial records related to President Trump, including any that were given to special counsel Robert S. Mueller III.

The bank responded on March 21 that it was preserving the documents requested but would hand them over only under subpoena, according to a copy of the letter from Brent Timberlake, the company’s counsel.

The request came from Oversight Committee Chairman Elijah E. Cummings (Md.), Financial Services Committee Chairwoman Maxine Waters (Calif.) and Intelligence Committee Chairman Adam B. Schiff (Calif.).

Two leading Republicans on Oversight, Jim Jordan and Mark Meadows, tried to head this off at What’s-In-Your-Wallet Pass. They warned that these demands weren’t substantive oversight to Capital One’s operations, but a political hit job on Trump that Richard Fairbank should resist:

“Probes aimed simply at harming the electoral prospects of a future candidate for office are improper on their face,” they wrote to Capital One Financial CEO Richard D. Fairbank.

They also complained that they weren’t consulted before the Democrats sent Fairbank a request on March 11 requesting a wide range of materials related to Trump’s finances and business holdings.

This would cross the infamous “red line” Trump supposedly laid down with Robert Mueller during the special counsel investigation. According to reporting at the time, Trump reserved the right to gripe publicly about Mueller but pledged to cooperate as much as possible — unless Mueller expanded the probe into his personal finances or those of his family members. Once or twice reports leaked out that Mueller was about to expand in that direction, but nothing much came of it. Reportedly, Mueller’s team quietly let Trump’s attorneys know that the reports were erroneous.

There’s nothing mysterious about this, though, except to what extent Trump can keep House committees from getting the materials. Banking records in the US are generally private but there are plenty of exceptions to that for investigators. Unlike with Mueller, Trump can’t fire House committee members if they cross his “red line,” and he’ll have to go to court to challenge their subpoenas. A federal court might require a House committee to make a show of reasonable suspicion of a specific crime before approving such a subpoena, or maybe it won’t. The appellate level will likely take that more seriously, but we can’t pretend that precedents don’t exist for probes of personal finances of presidents and their families. Remember Whitewater, among others?

Trump came out firing yesterday when asked about the House effort to get to his tax returns. The president responded by telling House Democrats that they could talk to his attorneys — and his Attorney General too:

The White House could attempt to block the release of President Trump’s tax returns to Democrats, senior officials signaled on Thursday, an unprecedented step that might lead to a constitutional challenge and catapult the issue into federal court.

In an indication of how the standoff might escalate, Trump himself suggested that the Justice Department could become involved — even though Democrats directed their request to the commissioner of the Internal Revenue Service.

“They’ll speak to my lawyers and they’ll speak to the attorney general,” Trump said during an unrelated event in the Oval Office when asked about the Democrats’ request for six years of his personal and business tax returns.

What would William Barr have to do with such a demand? Perhaps something, although theoretically the AG would have no direct role.  It’s more on Treasury Secretary Steven Mnuchin to make the determination, as the IRS answers to Mnuchin, not Barr. Its legal team is guided by the Office of Legal Counsel, which advises all executive branch agencies on the law. That does operate within the Department of Justice, but it’s supposed to be somewhat independent of the AG, whom it also advises on legal matters.

The details do matter but the main message matters more. If House Democrats cross the red line, Trump is warning that he’ll go to war over it. That strategy is just as unsurprising as House Democrats’ strategy in triggering it.