President Trump said Wednesday that his White House will be "fighting all the subpoenas" from the House. He will also continue refusing to allow testimony from current and former administration officials, on the political — not legal — grounds that House Democrats are partisan and not "impartial people." Trump has always treated the theoretically co-equal legislative branch as a younger sibling, but since Democrats took control of the lower house in January, his view of Congress has apparently shifted from cute plaything to annoying pest.

Some White House officials and Trump allies argue this is a winning strategy to prevent Democrats from obtaining potentially damaging information on Trump until after the 2020 election, even if they ultimately lose their effort to block the subpoenas in court. "Trump's White House appears to have figured out the secret of congressional oversight: There's not much Democrats can do if they say no to everything," Axios notes. But Democrats aren't without options. Here are some tools House Democrats are using or might employ to enforce their oversight responsibilities:

1. Contempt
The House can vote to hold officials in civil or criminal contempt of Congress, opening them up to lawsuits or criminal charges. And in January, The Washington Post reports, House Speaker Nancy Pelosi (D-Calif.) backed an obscure rule giving a three-person panel — made up of House Majority Leader Steny Hoyer (D-Md.), House Minority Leader Kevin McCarthy (R-Calif.), and Pelosi herself — the power to approve civil contempt citations without a full House vote, as a "way to streamline the process" if the White House "sticks with its strategy."

But the Justice Department would have to prosecute those cases, and recent contempt citations — former Attorney General Eric Holder, George W. Bush officials Harriet Miers and Josh Bolten — languished for years, ending in settlements during the next administration.

2. Enforce subpoenas
"Many years ago, Congress ceased trying to enforce its own subpoenas and instead generally seeks to outsource enforcement to the other branches," legal expert Ross Garber tells Politico. Going through the courts is a slow process, but on Wednesday, Rep. Gerald Connolly (D-Va.) proposed taking back that power, the Post reports, suggesting Democrats instruct "the sergeant at arms to find and jail those who defy subpoenas until they relent, a step Congress hasn't taken since the 1870s."

3. Lean on businesses and individuals
The House Judiciary and Oversight committees aren't just subpoenaing the Trump administration but also "businesses, banks, and private individuals" who have done business with Trump or were flagged by Special Counsel Robert Mueller, Politico reports. Companies — especially ones with government business — and individuals are much less likely to defy Congress, and Trump's lawyers have to sue to stop them.

Judiciary Committee Chairman Jerrold Nadler (D-N.Y.) also recently proposed fining or even jailing individuals who don't comply with subpoenas, and Oversight Committee Chair Elijah Cummings (D-Md.) warned Wednesday that "employees and their personal attorneys should think very carefully about their own legal interests rather than being swept up in the obstruction schemes of the Trump administration."

4. Use the power of the purse
"House Democrats have also discussed the idea of tying federal funding to requirements that department and agency heads comply with their investigations," the Post reports. "They've also considered finding ways to enforce an obscure law that bars officials from being paid if they hinder another federal employee from cooperating with Congress."

5. Use the court of public opinion
Trump insisted Wednesday that he had "been the most transparent president and administration in the history of our country by far." But blanket stonewalling "totally undercuts the argument that we've been transparent" and there's "no criminal wrongdoing," a former senior White House officials tells Axios. "Now we look like we've got something to hide and we're not being open and transparent." A source familiar with the House Democrats' investigative plans adds that they "haven't even begun focusing on issues that can be localized" or highlighted to show how Trump's behavior negatively affects voters vulnerable districts or red states.

6. Impeachment
While Trump says he isn't worried about being impeached, his Twitter feed suggests otherwise, and some House Democrats say Trump's blanket obstruction makes impeachment more likely. But presidents aren't the only officials subject to impeachment. On Monday night, Rep. Jared Huffman (D-Calif.) told colleagues they should consider impeaching the IRS commissioner if he refuses to turn over Trump's tax returns.

"The idea that the IRS commissioner would instead follow the direction of Donald Trump's legal team instead of statutory directive just can't stand," Huffman told the Post. Impeachment of the heads of departments and agencies "is the constitutional backstop when executive branch officials refuse to follow the law."

7. Leaks
If Trump won't play ball, "one trend we've been seeing more and more, and a way we can get new information, is from whistleblowers," a senior Democratic aide tells Axios. Say what you want about Trump's White House, but it has never lacked for leakers. Maybe that's what he means by "most transparent."