WASHINGTON (Reuters) - The U.S. House of Representatives on Friday passed legislation that Democrats say will lessen the influence of big-money interests in federal elections, make voting easier and tackle “gerrymandering” that skews the makeup of congressional districts to favor particular political parties.

In a warning shot to Republican President Donald Trump, Democrats included a provision in the bill requiring all presidents and presidential nominees to make public their tax filings - something the current White House resident has steadfastly refused to do.

Some congressional investigators think those returns could shed light on whether Trump has had any business dealings in Russia that could have influenced his relations with Moscow, either as a presidential candidate or as president.

In a party-line vote of 234-193, the House approved the “For the People Act,” a bill House Speaker Nancy Pelosi promised in the 2018 congressional election campaigns that Democrats would pursue to help clean up American politics and foster voting rights.

Shortly before passage of the bill, Pelosi said it “ends the dominance of big, dark, special-interest money in politics and it empowers small donors and the grassroots” and “fights voter suppression.”

But the measure is likely to become merely a campaign tool for Democrats as they try to expand the number of seats they hold in the House and to capture the Senate and White House in the 2020 elections.

Senate Majority Leader Mitch McConnell, a Republican, has repeatedly attacked the Democratic bill, leaving little chance for it in the Republican-controlled Senate.

Backers say the legislation would make voter registration easier, expand voting hours on election days, restore voting rights to U.S. citizens who have served prison sentences for felonies and shore up voting machines and election infrastructure against cyber attacks and other interference.

The legislation comes after U.S. intelligence agencies found that Russia meddled in the 2016 American presidential elections and as Moscow has been accused of trying to influence the outcome of elections in other democracies. Russia has denied meddling in the 2016 election.

Special Prosecutor Robert Mueller has been investigating whether Trump’s campaign colluded with Russia in a way that was beneficial to his successful 2016 White House bid. Trump has denied there was any collusion between his campaign and Moscow, and has labeled Mueller’s probe a “witch hunt.”

The House bill would require states to establish independent commissions for drawing congressional districts, instead of the power residing mainly in the hands of state governors and legislatures.

Tougher ethics standards would be imposed on members of Congress, and small campaign donations would be matched with federal funds to try to blunt the influence of big donors.

Calling it the “Democrat Politician Protection Act,” McConnell has lambasted the legislation, arguing it would give Washington too much control over elections while unnecessarily using tax dollars for political campaigns.

As Senate majority leader, McConnell has the power to largely decide what legislation is debated in the upper chamber.