Sen. Jon Tester (Mont.), a Democratic moderate, on Monday joined maverick Sen. Joe Manchin (D-W.Va.) in calling for fellow Democrats to pay for all of the massive human infrastructure spending bill they are drafting behind closed doors.

Tester told reporters outside the Capitol that he wants “100 percent” of the bill, which Senate Majority Leader Charles Schumer (D-N.Y.) plans to pass under the budget reconciliation process, to be paid for.

That means Democrats will need to come up with at least another $600 billion in offsets if they are to meet their $3.5 trillion spending goal and get Tester’s vote.

“I’m going to be looking at a couple things: Where the money is being coming from, how it’s being raised and then how it’s being utilized moving forward. We have a lot of work to do,” Tester said.

Most of the attention on potential Democratic defections has been focused on Manchin and centrist Sen. Kyrsten Sinema (D-Ariz.), but other moderate Democrats are leery about passing another massive spending bill when the national debt is fast approaching $29 trillion.

A tax package unveiled over the weekend by House Ways and Means Committee Chairman Richard Neal (D-Mass.) would raise an estimated $2.9 trillion, falling short of covering the top-line spending number outlined by the Senate- and House-passed budget resolutions.

Neal’s package, which would raise the corporate tax rate from 21 percent to 26.5 percent — just short of the 28 percent mark endorsed by President Biden — omits several elements that are popular among Democrats.

Chief among them is a proposal backed by the White House and Senate Finance Committee Chairman Ron Wyden (D-Ore.) to eliminate stepped-up basis for unrealized capital gains when assets are passed on to heirs.

The tax code currently does not impose capital gains taxes on stocks and other assets at death, and heirs now must pay capital gains taxes only on the accrued value of inherited assets calculated from the date at which they are inherited.

Tester, whose family owns an 1,800-acre farm, on Monday said he’s glad the proposal to eliminate stepped-up basis for unrealized capital gains has been dropped from the House package.

“It’s a good thing,” he said.

Tester was less certain about Neal’s proposal to set the corporate capital gains rate at 26.5 percent.

“It depends on a couple things. Number one, what’s it raise in dollars? Number two, how it’s going to be spent?” he said. “I think what’s really important is how the money is spent.” 

“The bottom line is if it’s not spent correctly, then we’re making a big mistake. If it is spent correctly, then it’s the right thing to do,” he said.

Tester said the Democratic package remains fluid.

“There have been discussions all the time, but nothing has been put in stone until today,” he said. “I’m already starting to get briefs from my staff on what’s in it.”