Money.

Period.

It starts one of two ways, either 290 votes in the House of Representatives, or a call for a Constitutional Convention by 34 states.

To give you some idea how hard this is, they recently took 15 votes to get a simple 218 vote majority to pick their own leader. The 290 vote threshhold was surpassed by the 311 vote majority to remove George Santos. That’s the kind of agreement that needs to happen.

Once you get that, it moves to the Senate where you need a 67 vote majority. The Senate has been crippled now with the filibuster requiring a 60 vote minimum to get anything done. 67 on a new amendment is unlikely.

The 34 vote convention path has never actually worked, although 28 states have signed off on a new convention, 6 more are still needed.

However it shakes out, either through the House and Senate or a new constitution, now you need ratification from the State Houses and that’s the tricky bit.

State legislatures will need to vote up or down on it and it takes effect once 38 states pass it.

To put this in perspective, in 2020:
Biden won 25 states, the floating EC vote in Nebraska, and Washington D.C.
Trump won 25 states + the floating EC vote in Maine.

So to get an amendment passed, you need all of one side + 13 from the other side.

Want to ban guns? All 25 Biden states +13 Trump states.

Want to ban abortion? All 25 Trump states +13 Biden states.

But it’s not that easy either…

Remember, the vote is done by statehouses, and of those 25 Biden states, 6 are Republican led.

I forget which one but one of the Supreme Court Justices has stated that they’ve estimated it could take as little as 2% of the national population to halt an amendment by starting from the smallest state and getting half plus 1 in opposition.

The kind of monumental change that a lot of people think this country needs will have to come via a convention, and right now neither side wants to pull that trigger out of fear that the other side will be able to edge them out and inaugurate a constitution that completely wipes out all their issues and positions.

Basically it would require either a compromise of proportions unseen just to even begin talking about it, that or the absolute devastation of one side to the degree that they would be completely incapable of stopping an absolute steamroll at the hypothetical convention.

First you’d need to unfuck American politics. Like actually. Anything that isn’t drastically necessary and completely unpolitical or wildly popular and supported by a party representing a significant majority of people and states.

To put it into context: this is the equal rights amendment and it was a political shit show. Its text is uncontroversal, already was the law, and also very necessary as when it was proposed women not being fully independent people in the eyes of the law was in living memory. The equal rights amendment is not a part of the United States constitution. Some states repealed ratification. If you want to understand why no amendments will happen the means for that to happen were built to kill the ERA. Modern extreme factionalism and the American right wing committing to antifeminism as a political stance were part of this.

We still need the ERA, it provides protection to everyone regardless of gender by demanding the government treat them regardless of gender. But we need more amendments, more controversial ones, like an explicit right to privacy that no court nor legislature can violate.

I doubt America will survive long enough to get another amendment

A functional government. And that ain’t happening.

You said it, the details are going to vary too much between specific attempts to give a single answer.

This is one of those rare times that reddit would have been perfect because of r/askhistorians. You could at lest have probably gotten partial answers for specific amendments and cobble together a guesstimate on what a modern effort would take.

But just from a bit of memory based on very old classes, you’d be looking at years of sustained groundwork to build support, and that’s going to be millions to billions of dollars spent in propaganda (which isn’t an inherently negative word when used broadly), and awareness raising, plus man hours beyond my ability to guess.

I know that even that last one took a lot of work to get started.

The only amendment with any real push behind it is the ERA. And that’s complicated because of how long the process has been.

First step - both chambers of Congress approve a draft amendment by a 2/3rds vote, or a “convention” called by the legislatures of the states (understood to mean 2/3rds of the states) adopts a draft amendment.

Then 3/4ths of the legislatures have to pass the adopted amendment, or conventions in 3/4 of the states (which a state’s legislature can call).

It would take a new Constitutional Convention to be proposed, where every single state will demand presence. Nothing will survive a vote unless it is a two-thirds majority.

It would take a fucking massive financial investment in some grassroots organization to start the ball rolling with signature petitions circulating every human alive in every state to even be considered slightly noticeable by the media, then it might take off.