When President Biden rolls out his next big economic package this week, it could do more than trigger a national debate about how best to invest in our future. It might also explode a big Washington myth, one repeated so often that it has become accepted as truth.

It’s the idea that the GOP is moving left on economics in some fundamental way, largely due to former president Donald Trump’s influence. While there is ideological ferment in the GOP — among the “conservative populists” challenging GOP orthodoxy in some ways — the debate over Biden’s “Build Back Better” plan will likely reveal the true limits of that ferment.

Biden’s second economic package — which will likely total at least $3 trillion and will be introduced Wednesday — will have two parts: one focused on rebuilding physical infrastructure, and the other on rebuilding “human capital.”

Each one will likely reveal just how limited the GOP’s supposed move to the left on economics really is.

Let’s start with infrastructure. This part would spend up to $2 trillion on rebuilding roads, bridges, power grids and waterways. It will include big investments in a decarbonized future, such as Biden’s pledge to build 500,000 electric-car charging stations.

Some Republicans do appear to support the first half. But they’re already balking over Biden’s proposal to help pay for it by undoing parts of the Trump tax cuts, particularly the benefits they showered on corporations and the wealthy.

Indeed, well in advance of the plan even being released, Senate Minority Leader Mitch McConnell (R-Ky.) has already declared infrastructure will be a “Trojan horse” for “massive tax hikes and other job-killing left wing policies.”

You can already see how this game will unfold. Republicans will declare that infrastructure repair could be bipartisan. But Republicans will add both that we can’t spend nearly what liberals want because of the deficit and that we can’t raise taxes to pay for it, because that will be “job-killing.”

The same old, warmed-over nonsense

Sound familiar? It should. As CNN’s John Harwood points out, Republicans claimed tax hikes for the rich under former presidents Bill Clinton and Barack Obama (the latter to fund the Affordable Care Act) would prove to be job-killers.

“In neither case was that proven to be true,” Harwood notes, citing “tremendous job growth during the Clinton years” and a “record streak” of it under Obama.

In other words, Republicans are already serving up the same warmed-over nonsense about tax hikes on the rich that we’ve heard for decades.

“We just don’t see in the historical record that tax increases lead to reduced jobs,” Chye-Ching Huang, the executive director of New York University’s Tax Law Center, told me.

By contrast, Huang noted, the record shows that high-end tax hikes support the sort of public investments that “strengthen economies in a way that benefits workers and families,” which is especially visible in countries “that invest a whole lot more in modernizing infrastructure.”

You’d think conservative populist senators would break from GOP orthodoxy here. For Trump, the (false) promise of infrastructure repair was a key component of his national-greatness Trumpism. Now it should easily fit into conservative nationalist ideas about remaining competitive with China.

But there are reasons to be skeptical that the conservative populists will support anything like this, even minus its green energy component. Sen. Josh Hawley (R-Mo.) endorsed Trump’s tax cuts in 2017. And in this case, it’s likely party pressure to remain united against Biden’s agenda will preclude any possibility of cooperation.

More broadly, as historian Lawrence Glickman notes, the Trump-era GOP is notable for a fusion of sorts. It has moved in a more authoritarian direction (following Trump) while not evolving leftward on economics along with a country that is shifting in that direction.

For instance, a new ABC News/Ipsos poll finds large majorities of Americans support Biden’s handling of the economy and covid-19, a very broad endorsement, coming after Biden’s initial $1.9 trillion rescue plan.

So majorities are moving toward an embrace of much more robust government and public spending to address large public problems. Yet every Republican voted against Biden’s first package.

Republicans can’t even support a child tax credit

The “human capital” side of Biden’s next big plan will likely tell the same story. It’s understandable that Republicans might oppose more liberal elements. But Biden’s plan will also seek an extension of the child allowance — which will send most families at least $3,000 per child over the next year.

This, too, is something Republicans challenging GOP orthodoxy should support. It’s a pro-worker policy that’s also pro-family in a way conservatives should like: It sends families money without “liberal social engineering.”

Yet when Sen. Mitt Romney (R-Utah) proposed an even more generous child allowance, conservative populist GOP senators panned it as “welfare.” They reverted to a Paul Ryan-esque depiction of the welfare state as a debilitating “hammock,” an ideological throwback just as trapped in the past as their current rhetoric about tax hikes as “job-killers.”

The child allowance should be “a sweet spot for conservative populists,” Samuel Hammond, an analyst at the Niskanen Center, told me. “If they can’t move on something as pro-family and simple to understand as the child allowance, it raises the question of how real this conservative populist moment really is.”

“The Republican Party isn’t evolving on economics,” Hammond added. His stark conclusion: “The question is, what do Republicans believe in at all?”

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