Chances of President Biden convincing Congress to pass his tax hike on the wealthy—a package that one estimate says will impose a rate of up to 61% on rich taxpayers—appear to be dwindling, as Democrats in high-tax and farming states signal their opposition.

The revenues the capital gains taxes would generate are central to paying for Biden’s ambitious $6 trillion budget plan. That plan seeks to raise the top tax rate on capital gains to 43.4% from 23.8% for households with income over $1 million. Biden would also change the tax rules for unrealized capital gains held until death, doubling the rate to 40% with an $11.7 million exemption. The taxes would be retroactive to April.

While the plan is ambitious, all 50 Democrats in the Senate must vote yes if Biden hopes to pass his budget using reconciliation, and that would require Vice President Kamala Harris to cast the tie-breaking vote.

“Given the current opposition in Congress with the margins just about as tight as they could be, if even one Democrat senator opposes this proposal, it won’t go anywhere,” Garrett Watson, senior policy analyst for the Tax Foundation, told Financial Advisor magazine. “It’s a significant departure of what we have now and would increase the tax rate on wealth to nearly twice the effective tax rate any asset faces today.”

Watson called Biden’s plan to tax unrealized gains at death and levy the estate tax at the same time “quite unique. Traditionally estate tax law has allowed for a step-up in the basis of transferred assets so that they were not hit by the capital gains tax and the estate tax at the same time. Combining both taxes results in an effective tax rate of 61%,” Watson added

The Tax Foundation issued a report recently that laid out why it sees Biden's plan raising the rate to 61% for some taxpayers.

“For an asset worth $100 million (all of which is a capital gain for the sake of simplicity), the two changes would mean an immediate capital gains tax liability of $42.9 million at the time of death. Upon paying the capital gains tax at death, the value of the $100 million asset falls to $57 million for the purposes of the estate tax. After subtracting the $11.7 million exemption, the 40% estate tax rate is levied on the remaining $45.3 million in assets to produce an additional estate tax bill of about $18.1 million,” Watson wrote in a Tax Foundation blog. The total tax bill on the $100 million asset under Biden’s capital gains plans is $61 million, or 61%, he concluded.

The hikes are so steep a growing number of Democrats facing re-election are balking at the proposal. Sen. Mark Warner (D-Va.) told reporters he wants to maintain a lower tax rate for capital gains than for ordinary income. Lawmakers from farm states, such as Sen. Jon Tester (D-Mo.) and Rep. Cindy Axne (D-Iowa), object to Biden’s doubling capital gains at death. And Sens. Joe Manchin (D-W. Va.) and Kristen Sinema (D-Ariz.) don’t like Biden’s proposed $15 federal minimum wage mandate.

“Right now, Democrats have a pretty mixed reception to Biden’s proposal and Republicans are very skeptical or oppose it,” Watson added. “Even in the House, Democrats only have a half-dozen vote lead and if they lose them over their demand for a SALT repeal or reduction, that could be a problem.”

If the White House decides to pare back the tax on unrealized gains at death, that will also likely restrict how high it can raise capital gains taxes, Watson said. If you raise the rate too high, a significant portion of people will decide not to sell and will hold on to assets. Tax avoidance reduces revenues.

“I think it is unlikely that the Congress will pass President Biden's tax increases,” said Herschel V. Clanton president of Chancellor Wealth Management Inc. in Atlanta.

“While it is possible that the votes in the Senate would break down to 50-50, with Vice President Harris breaking the tie, that assumes that all 50 Democrat senators are confident of their re-election." he said. "While we don't pretend to predict the future, we have been sharing this perspective with our clients. They are all aware of the White House proposals.”

The owners of “businesses where there would be liquidity issues and farms will both create a big barrier for these proposals,” Watson said. “There are proposals that would allow taxpayers to pay a tax over time, say eight or 10 years. But even that has poor optics.”

Making matters worse is the fact that Biden’s $6 trillion budget assumes that his proposed capital-gains tax rate increase took effect in late April, meaning that it would already be too late for high-income investors to realize gains at the lower tax rates if Congress agrees, the Wall Street Journal reported in May.

“Clients can’t wait to pay more of their ‘fair share,’” joked Jeff Farrar, co-founder, partner and executive managing director at Procyon Partners in Wilton, Conn. “Even Biden voters hate the fact he's raising rates and doing it retro is even more of a stinker. Clients’ anxiety is seven on a scale of 10. Even clients who won’t be directly impacted are worried about its impact on the equity markets."

Watson predicts Congress will likely pass a modified budget plan, but what the Biden administration and lawmakers decide to include and what will be removed remains to be seen.

If Democrats try to use reconciliation to pass their plans “they may only have one shot at it. The Senate parliamentarian said yesterday they can use reconciliation twice, but it can’t be purely to avoid a filibuster,” Watson said.

While the White House continues to lobby lawmakers, combining the budget with the Biden family and jobs plans “comes with an optics issues over the sheer size of the spending and tax increases.” Watson said.

Gregory Collier, president of Collier Financial Solutions Inc. in Mount Dora, Fla., agreed that it is likely that Congress will pass some form of tax legislation and said his clients have anxiety about it. “Many know that taxes will be increased on most taxpayers. The amount of proposed spending in Washington is a major concern,” he said.

The prospect of a retroactive doubling of capital gains taxes is also troubling, he said. “Yes, I am bothered that they would even consider proposing such high rates on long-term gains. Retroactive enactment does not allow for planning and mitigation strategies. However, it may benefit philanthropy,” Collier said.