Donald Trump spoke at Capitol Hill on Thursday, marking his first appearance there since supporters of his rioted at the site on January 6, 2021.
His appearance came after Democrats said he was not welcome to return.
In his speech, Trump criticized US aid to Ukraine and suggested raising tariffs to replace the US income tax. He also called Milwaukee, the city hosting his party's presidential convention, "horrible."
In separate meetings with Republicans in the House of Representatives and the Senate, Trump sought to mend divisions ahead of the November 5 election that could see his party win control of the White House and both chambers of Congress.
Trump floated the idea of reducing the US income tax and replacing it with tariffs, said Representatives Thomas Massie and Marjorie Taylor Greene.
Participants said he shook hands with Senate Republican Leader Mitch McConnell, despite their frosty relationship, and encouraged hard-liner Greene to "be nice" to House Speaker Mike Johnson, after her failed attempt to depose him.
"There's tremendous unity in the Republican Party," Trump said after the Senate meeting.
But Republicans scrambled to explain after several media outlets reported that Trump privately called Milwaukee a "horrible" city, roughly one month before he is due to receive his party's presidential nomination there.
That could potentially alienate residents of the biggest city in Wisconsin, one of a handful of competitive states that will determine the outcome of the election.
A campaign spokesperson and several Republican lawmakers said Trump was referring to what they said were the city's problems with crime and voter fraud. A nonpartisan audit of the 2020 election in Wisconsin found no evidence of irregularities.
Memories of January 6
Trump's supporters stormed the Capitol on January 6, 2021, fueled by his false claims that his defeat was the result of fraud.
"After inciting a deadly insurrection that defiled the halls of Congress, how dare Trump show his face on these grounds?" Democratic Representative Bennie Thompson said in a statement.
The Biden campaign on Thursday began running an ad in battleground states highlighting the violence of January 6.
Republican lawmakers said Trump told them he would work to expand the party's narrow 218-213 House majority and take control of a Senate that Democrats currently lead 51-49.
Trump also advised House Republicans not to push a national ban on abortion and urged them to abandon the intra-party squabbling that has hobbled their effectiveness, lawmakers said.
It was Trump's first face to face meeting with McConnell since the January 6 attack. The two had not spoken since a few weeks before then, when McConnell affirmed Biden's 2020 victory. Two moderate Republican senators, Susan Collins and Lisa Murkowski, skipped the event.
McConnell did not appear with Trump at a news conference after the meeting.
Tips and Tariffs
Trump also urged lawmakers to cut taxes on income from tips, an idea he first floated on Sunday to appeal to service workers, multiple lawmakers said.
Trump used tariffs aggressively during his 2017-2021 term in office, placing levies of up to 25% on a wide range of Chinese products as one of many efforts to thwart competition.
Senator Mike Rounds said that cutting taxes on tips could help Republicans win over working-class voters.
"If there was something we could do to really energize that particular segment of the population, that might be a real popular thing to do," Rounds told reporters.
Biden's support among voters without college degrees or living in households earning $50,000 a year or less has fallen sharply, Reuters/Ipsos polling shows, though large numbers of those voters have not shifted their support to Trump.
Trump also criticized a $60 billion aid package for Ukraine that recently passed with Republican support, lawmakers said.
"He's like, if Ukraine wins, what will be the benefit?" Republican Representative Don Bacon told reporters.
Trump told Republicans they should allow states to set their own policies on abortion, rather than push for a nationwide ban following the Supreme Court's 2022 decision that ended the nationwide guarantee of abortion access. Many in the party want to outlaw the procedure entirely.
"He reiterated he thought that was the right decision, that some states will do one thing and some states will do another," Republican Representative French Hill told reporters.
Trump also spoke to the Business Roundtable, an association of more than 200 corporate chief executives.