U.S. Sen. Mark R. Warner, D-Va., the ranking member the Intelligence Committee, got some grief from fellow Democrats for suggesting that nothing much would change with respect to the Russia investigation if Democrats take back the majority in November. He asserted that voters “will be tired of it if this is not wound down in this calendar year.” He is right in this regard: The real action is now with special counsel Robert Mueller. It will be his report that will determine next steps regarding Trump and his various associates.

Democrats, however, will have much to do if they seize the majority in either the House or Senate because Republicans in the majority have ignored their constitutional obligations. This list of topics for open hearings should get them started:

• A full accounting of President Donald Trump’s receipt of foreign emoluments to determine whether there has been a constitutional violation or even bribery. The same should be conducted for other “senior officials,” namely his daughter and son-in-law.

• A thorough review of the deaths of American servicemen in Niger.

• Hearings on presidential warmaking powers, including the executive branch’s claim to nearly unlimited military powers (revealed in a case that forced the administration to produce its justification) and any assertion that a first strike on North Korea or Iran could be authorized without a congressional vote. (To his credit, U.S. Sen. Bob Corker, R-Tenn., the chairman of the Foreign Relations Committee, held one hearing; more are needed.)

• A deep dive into corruption and misuse of taxpayer funds at the Environmental Protection Agency under Administrator Scott Pruitt.

• An examination of all contacts between the White House and the Justice Department with respect to specific enforcement and/or criminal matters.

• An investigation into Russian oligarchs’ investments in the United States, including — but by no means limited to — the president’s real estate properties.

• Robust oversight of the Department of Homeland Security, including the family-separation policy of this administration and its expulsion of those with temporary protected status.

• An inquiry into abuse of the intelligence oversight process by members of Congress (perhaps via ethics committees).

There is nothing unusual about these topics. What is unusual is that, on items of extreme importance to our national security, the rule of law and operation of government, next to nothing has been done by the current crop of Republicans. Contrary to the GOP’s howls that Congress will be paralyzed if Democrats take charge, the normal hearing and oversight process can take place alongside the rest of Congress’ business (not that Republicans have done much of anything since passing the tax cuts). Republicans apparently have gotten so used to giving Trump a pass that they’ve forgotten what real oversight looks like.

Hearings have several purposes.

Foremost, without oversight there is little transparency; without transparency there can be no accountability. It may well be that after a full investigation into the operation of the EPA, either censure or impeachment of the agency’s administrator is warranted. If members of Congress have impermissibly leaked classified material, they should be punished.

Second, under Republican control, Congress has done practically nothing to reclaim its constitutional powers. Once the extent of scandals or problems is fleshed out, legislation can and should be introduced to address specific concerns. To the extent the White House has been reaching into the Justice Department to tip the scales on enforcement and investigative matters, we will need reforms such those passed by the post-Watergate Congress.

Third, financial corruption, conflicts of interest and use of office for self-enrichment as well as other abuses have multiplied in the executive branch. Complete disclosure and divestment for presidents and vice presidents should be on the table.

Democrats will be obligated to take up these and a slew of other issues (protecting voting rights and expanding voter access, for example) precisely because Republicans have allowed abuses to go on under their noses. Any legislation going forward will affect both Democratic and Republican administrations.

In short, the first step in repairing damage to our democracy will be for Congress to do its job. That would be a refreshing change.