WASHINGTON (Reuters) - When the Democrats take over the U.S. House of Representatives in three weeks, their first order of business is expected to be a wide-ranging bill about political corruption, voter disenfranchisement and cleaning up campaign finance.

FILE PHOTO: Newly elected members of Congress walk down the steps of the Capitol as they arrive for a class photo for incoming freshman members of the U.S. House of Representatives on Capitol Hill in Washington, U.S., November 14, 2018. REUTERS/Carlos Barria/File Photo

Aimed at sending a message, the legislation is unlikely to become law with Republicans still in control of the Senate and the White House. But it will offer guide posts to aggressive oversight to come later in 2019 of Donald Trump and his presidency.

An outline of the bill, titled H.R. 1, shows it would require presidential candidates to disclose their tax returns, which Trump has refused to do despite decades of precedent.

Members of Congress would be barred from serving on the boards of for-profit corporations under the bill. It would also overhaul the U.S. Office of Government Ethics, create a new ethical code for the U.S. Supreme Court and strengthen oversight of lobbyists and foreign agents.

The bill calls for automatic, early and online national voter registration, as well as an end to partisan gerrymandering of House voting districts, the practice of changing electoral district boundaries to favor a party.

Political groups would have to disclose their donors. The largely ineffective Federal Election Commission would be overhauled. Disclosure rules for digital political ads would be harmonized with rules for broadcast ads.

“H.R. 1 is about putting a positive set of reforms out there to fix some of the systemic problems we have,” said Democratic Representative John Sarbanes, who is leading the effort.

“We want to make a declaration early that we bring a different cultural standard,” he told Reuters.

The bill is expected to be introduced soon after the 2019-20 Congress convenes on Jan. 3, with hearings to follow. House committees will prepare separate segments of the bill for a House floor vote, due within the first 100 days of 2019.

U.S. voters ended Republican control of the 435-member House in congressional elections on Nov. 6 and handed it to Democrats. Republicans expanded their majority hold on the 100-seat Senate.

Winning control of investigative committees, House Democrats are preparing to probe Trump’s businesses, his taxes and allegations of corruption among top administration officials.

House committees involved in crafting H.R. 1 are expected to examine oversight themes in the early weeks of 2019.

While the bill addresses long-standing problems in Washington, House Democrats say that Trump’s presidency has increased the need to strengthen democratic institutions.