US Vice-President Kamala Harris has told supporters she supports eliminating taxes on tips, taking a similar position to her rival Donald Trump in an effort to win over service workers.
Harris and her Democratic running mate, Minnesota Governor Tim Walz, wrapped up a multi-day tour of battleground states on Saturday with their stop in Nevada, a western state that could play a pivotal role in the November presidential election.
"It is my promise to everyone here when I am president we will continue to fight for working families, including to raise the minimum wage and eliminate taxes on tips for service and hospitality workers," Harris said.
Harris said she would work to drive down consumer prices, vowing to "take on big corporations that engage in illegal price-gouging" - corporate landlords that unfairly raise rents on working families - and big pharmaceutical companies to lower drug prices.
Trump, who told a rally in Las Vegas in June that he would seek to end taxation of income from tips, accused Harris of stealing his policy proposal.
"Kamala Harris, whose 'Honeymoon' period is ENDING ... just copied my NO TAXES ON TIPS Policy," Trump said on his Truth Social app. "The difference is, she won’t do it, she just wants it for Political Purposes!"
A Harris campaign official said her proposal would require legislation to be passed by Congress.
"As president, she would work with Congress to craft a proposal that comes with an income limit and with strict requirements to prevent hedge fund managers and lawyers from structuring their compensation in ways to try to take advantage of the policy," the official said.
Harris has been campaigning with Walz in Wisconsin, Michigan, and Arizona, all states that traditionally swing between supporting Republicans and Democrats in presidential elections.
To become president, a candidate need not win the national popular vote but must win 270 electoral votes.
Each state has electoral votes based on its population, making the swing states especially important.
Harris will travel to San Francisco in her home state of California on Sunday, where she is due to attend a fundraiser with former House Speaker Nancy Pelosi.
Almost 700 people are expected at the event, which is expected to raise more than $US12 million ($A18 million), a campaign official said.
Harris and Walz, whose selection she announced in Pennsylvania - another swing state - on Tuesday, are seeking to maintain and build on the momentum that she has generated since President Joe Biden stepped aside as the party's standard-bearer in July.
Harris was leading Trump, the Republican former president, by four percentage points each in separate polls conducted in Wisconsin, Michigan and Pennsylvania, another swing state, by the New York Times and Siena College - a marked difference from polls taken before Biden quit the presidential race.
The Trump campaign released a memo from its chief pollster Tony Fabrizio pushing back against the results.
"Once again, we see a series of public surveys released with the clear intent and purpose of depressing support for President Trump," Fabrizio said.
Nationally, Harris was ahead of Trump by five percentage points, 42 per cent to 37 per cent, in an Ipsos poll published on Thursday, widening her lead from a July 22-23 Reuters/Ipsos survey, which found her up 37 per cent to 34 per cent.
Harris has raised hundreds of millions of dollars and held rallies with thousands of supporters since becoming the Democratic candidate, regularly eclipsing the smaller events that Biden held and drawing ire from Trump, to whom crowd size has always been an important barometer of political strength.
