• Senate Finance Committee Chair Ron Wyden said former President Donald Trump's new campaign promise to scrap income taxes on overtime pay is "as fake as his tan."
• Trump's spokesman accused the Oregon Democrat of "disrespecting hard-working Americans."
• Trump has already vowed not to collect taxes on workers' tips or on seniors' Social Security, among other proposals aimed at working-class voters.

Senate Finance Committee Chair Ron Wyden threw shade at Republican presidential nominee Donald Trump on Friday over Trump's latest campaign promise: to eliminate income taxes on overtime pay.

"Donald Trump is losing, and these tax proposals he's floating out of desperation are as fake as his tan," Wyden said in a statement.

The Oregon Democrat who leads the Senate tax writing panel said the former president "knows Republicans in Congress have no intention of passing this stuff."

"It's obvious his newfound concern for working people is a fraud," Wyden argued, "because as president he undermined overtime protections for workers."

He added, "You can always count on him to treat workers like chumps he can buy off with empty campaign promises here and there."

Trump campaign spokesman Steven Cheung fired back at Wyden, telling CNBC the senator "shouldn't be disrespecting hard-working Americans and taking money out of their pockets."

"But it's not surprising coming from a loser like Wyden who has a history of persecuting everyday Americans," Cheung added.

Trump unveiled the tax-free overtime proposal Thursday during his first campaign rally since his bruising debate Tuesday night against Democratic nominee Vice President Kamala Harris.

"As part of our additional tax cuts, we will end all taxes on overtime," he said at the rally in Tucson, Arizona.

"If you're an overtime worker, when you're past 40 hours a week, your overtime hours will be tax free," Trump said.

Trump has been campaigning for president for nearly four years, but Thursday was the first time he had mentioned a proposal to eliminate income tax on overtime pay. He claimed to have floated the plan to "some economists," and said their opinion was that "it would be unbelievable."

The Harris campaign called the surprise announcement Trump's "latest snake oil sales pitch," noting that the Justice Department under Trump declined to defend an Obama-era rule that would have extended overtime benefits to millions of workers.

Trump has already vowed to cut or erase a slew of other taxes if he wins a second term in the White House. He has said a Trump government will not collect income taxes on workers' tips or on seniors' Social Security. He also pledged to increase tax breaks for families with newborn children and others.

Harris has also said she opposes taxing tipped income.

The Penn Wharton Budget Model in late August estimated that Trump's tax proposals at the time would hike deficits by nearly $6 trillion over the next decade.

Goldman Sachs in a September analyst note said Harris' economic policies would lead to a bigger economic boost and stronger job growth in the next two years than Trump's plans would.

Trump has claimed his plan to impose sweeping tariffs on imports will yield a cash windfall that allows him to pay for many of his plans. Economists warn that those tariffs would most likely lead to higher consumer prices.