A top business world critique of Kamala Harris since becoming the Democratic nominee is her endorsement of plans from the Biden administration that would reshape how the assets of America's richest citizens are taxed.

But these plans — which include the taxation of unrealized capital gains on holdings not yet sold — would face an uphill fight on Capitol Hill even if Harris wins big. Many of the critiques also vastly overstate how far-reaching they would be.

That hasn’t stopped many wealthy figures — especially Trump-friendly ones — from casting these plans as part of a a broad-based attack on wealth and the business community from Harris.

"This path leads to bread lines & ugly shoes," Tesla ( TSLA ) CEO Elon Musk posted of the Harris economic agenda.

What triggered this reaction was partly the Harris/Walz campaign endorsement of tax increase ideas in President Biden's most recent budget proposal . That revenue, according to Harris aides, would pay for her "opportunity economy" programs that include a child tax credit and housing subsidies and more to come.

Two of those Biden tax plans now under the Harris umbrella are focused on capital gains and would indeed raise rates and also bring some "unrealized" gains in for taxation.

But they would only apply to America's richest households (even many of the literal 1% wouldn't be impacted) and would have more limited effects when it comes to some types of wealth.

The way the Biden White House has tried to cast the idea is as an effort to create a minimum tax rate for the top 0.3 percent of all households.

The end goal, according to a Biden White House summary , is that these households with massive assets pay the same "marginal rate on their income just like a high-paid worker pays on their wages."

A focus on 'unrealized' capital gains

The most controversial idea by far is a plan to tax the unrealized capital gains of households if their net worth exceeds $100 million. Unrealized gains are advances in net worth that exist on paper but are tied to an asset that hasn't been sold yet.

It's an echo of calls from figures like Sens. Bernie Sanders and Elizabeth Warren for a "wealth tax," but the effect here would be more limited.

Currently, capital gains aren't taxed until assets are sold for any income level, but this plan would open a thin slice of the richest Americans to a new minimum tax of 25% of their "income" — alongside a broader definition of income that includes some unrealized gains.

The case from many Democrats is that Americans with giant reserves are already able to borrow against these funds and earn income, so they should be taxed accordingly.

There are also provisions that could dampen the effects further by allowing taxpayers to spread out payments and delay some costs — albeit with a "deferral charge" — on some hard to liquify assets like startup companies or real estate.

In response, former President Trump has sought to charge that any limits on these plans would be quickly done away with.

A recent visit to a Las Vegas restaurant led the GOP nominee to baselessly charge the tax on unrealized gains "will soon be applied to small-business owners and you will be forced to sell your restaurant immediately."

Trump added that the idea was "beyond socialism."

Varied assessment of how capital gains overall would change

The overall capital gains system would also be in for changes if Harris was able to enact a second plank of the Biden plan.

That part calls for a higher capital gains rate, again for the richest Americans, than what exists now.

Long-term capital gains are currently taxed at 20% for the richest Americans. This plan would — at least for households making over $1 million a year — raise this rate to be in line with rich taxpayers’ overall rate.

The current top tax rate on wages is 37%, but both Biden and Harris are keen to raise that as well, to 39.6%.

"Preferential tax rates on long-term capital gains and qualified dividends disproportionately benefit high-income taxpayers," a White House document cited as the reason for the change.

Economists have also long criticized the plans — especially those around unrealized assets—as unworkable, not enough to solve the multi-trillion annual national deficit, and likely to lead to distortions.

Washington's Tax Foundation assessed that Biden's plan would levy "a complicated tax on a narrow segment of high-earning households in a way that's never been tried."

Biden aides push back that a universal tax rate on income could actually lessen distortions and remove the incentive for individuals to take compensation as capital gains over wages.

Why it's unlikely to ever happen — even if Kamala Harris wins

These two capital gains plans could raise more than $800 billion over the coming decade but are likely to face an uphill battle in Washington even if Harris wins and decides to make it a priority.

These plans are, after all, ones that President Joe Biden himself has been pushing for years. But he couldn't get them enacted even in 2021 and 2022 when Democrats had control of both the House and the Senate.

Many of these proposals "have been reiterated year after year because a Democratic Congress did not pass them," Brian Gardner, Stifel chief Washington policy strategist, said in a recent note to clients.

"This raises the question of whether things will be any different in 2025," he added.

If she wins, Harris could face a more inhospitable political climate than Biden faced when he took office with Democrats facing an uphill fight to keep control of the Senate.

"How much spending or how many tax cuts or tax proposals you're going to be able to offer is going to be limited by the makeup of Congress," said Jeannette Lowe of Strategas Securities in a recent Yahoo Finance appearance.

"There may be some restraints."

Ben Werschkul is Washington correspondent for Yahoo Finance.