As Democrats try to agree a $3.5 trillion spending plan, Sen. Joe Manchin - whose vote is essential - wants to cut the cost by almost 60%

• Sen. Joe Manchin said Sunday ge opposes Joe Biden's plans for a $3.5 trillion infrastructure bill.
• Biden needs support from Manchin, a Democrat, to get his bill passed by the Senate.
• Manchin said he would back a much smaller package of up to $1.5 trillion.

Sen. Joe Manchin on Sunday threatened to blow up plans by President Joe Biden and most Democrats for a $3.5 trillion infrastructure and environment spending bill.

The West Virginia senator, also a Democrat, said that he would only back Biden's spending package if it were cut back by more than half, to a maximum of $1.5 trillion.

The Senate is so finely balanced that without his vote there is no obvious way for the bill to pass.

Manchin is the leading Democratic skeptic of key Biden administration policies, and in interviews Sunday explained his opposed to the large sum.

"I cannot support $3.5 trillion," Manchin told NBC News' "Meet the Press", and said he opposes the vast new social spending included in the package.

He also objected to a proposed increase in the corporate tax rate from 21% to 28%, designed to help cover some of the spending.

Manchin said that he did not approve of the timeline in which the bill was being considered, citing a late-September deadline House Speaker Nancy Pelosi set to get the bill passed.

"We should be looking at everything, and we're not. We don't have the need to rush into this and get it done within one week because there's some deadline we're meeting, or someone's going to fall through the cracks," he said.

In an interview with CNN's "State of the Union", he said he could support a bill of $1.5 trillion, on the condition that it retains a "globally competitive" corporate tax system.

He voted in favor of the $3.5 trillion sum in a blueprint vote last week, but had said that his vote signified only that he wanted to keep the process moving.

Manchin repeated his position in TV interviews Sunday, including with ABC News.

"There's not a rush to do that right now. We don't have an urgency. Don't you think we ought to debate a little bit more, talk about it, and see what we've got out there?" he said.

Top Democrats last week expressed faith in securing Manchin's support, with White House Chief of Staff Ronald Klain telling CNN last week he believed that Manchin was "very persuadable" on the $3.5 trillion sum.

The bill is one of the cornerstones of Biden's legislative agenda, and would be one of the most ambitious attempts to reshape the US infrastructure and economy for a generation. It would also provide funding for expanded social care services and environmental programs.

There is currently a stand-off between Manchin and leading progressives in Congress, such as Sen. Bernie Sanders.

Manchin has urged that the House approve a bipartisan $1.9 trillion infrastructure bill passed by the Senate earlier in August before considering further spending measures.

But Sanders told CNN on Sunday that his progressive colleagues in the House won't approve that bill until the larger package is passed.