When is a budget not really a budget? The reporting on Donald Trump’s “skinny budget” proposal has focused almost exclusively on the big boosts in national-security spending and the major cuts almost everywhere else in discretionary spending. The fact that any White House budget is essentially out of order when it comes to the formal budget process, “skinny” or not, has been relegated mainly to footnotes — but it matters politically.

That’s good context to keep in mind when reading reports such as this from Politico about reaction to the proposal, especially from Republicans:

President Donald Trump’s budget proposal got a rough reception Thursday on Capitol Hill.

“Not our starting point.” “Not something that will fly around here politically.” “Congress will do its own budget.”

And that’s just the Republicans. …

Yet it’s clear that the Trump budget would gut programs favored by Republicans as well. And key GOP lawmakers in the House and Senate already are signaling they won’t move forward with Trump’s proposal.

Trump is about to find what other presidents have before him — lawmakers in both parties like to talk about cutting spending and reducing the deficit. But don’t cut their own pet program, or one that would cost them politically. That’s something that won’t do, no matter who is sitting in the Oval Office.

All of this is true, and not much of it is new. Barack Obama’s budgets got routinely ignored by Democrats too, even when they controlled Congress but especially so after they lost the House. Republicans trolled their opponents by forcing an up-or-down vote on Obama’s budgets in order to put Democrats either in a position of voting for cuts and spending that would be very unpopular with constituents (and make great fodder for campaign ads later) or publicly rebuking their own president. Guess which one they chose, every single time? Hint: It wasn’t loyalty to President Underbus.

While presidential budgets wound up playing no formal role in the budgeting process, they did set the tone and context for budget negotiations in Congress. That’s what Trump has done with this budget — setting the parameters of the debate, or in current parlance, shifting the Overton window to put some concepts within the realm of the possible:

Politicians are constrained by ideas, even if they have no interest in them personally. What they can accomplish, the legislation they can sponsor and support while still achieving political success (i.e. winning reelection or leaving the party strong for their successor), is framed by the set of ideas held by their constituents — the way people think. Politicians have the flexibility to make up their own minds, but negative consequences await the elected officeholder who strays too far. A politician’s success or failure stems from how well they understand and amplify the ideas and ideals held by those who elected them.

In addition to being dependent on the ideas that form the boundaries of the political climate, politicians are also known to be self-interested and desirous of obtaining the best political result for themselves. Therefore, they will almost always constrain themselves to taking actions within the “window” of ideas approved of by the electorate. Actions outside of this window, while theoretically possible, and maybe more optimal in terms of sound policy, are politically unsuccessful. Even if a few legislators were willing to stick out their necks for an action outside the window, most would not risk the disfavor of their constituents. They may seek the good of those who elected them, and even the good of the state or nation as a whole, but in pursuing the course they think is best, most will certainly take into account their political future. This is the heart of the Overton window theory.

So, if a think tank’s research and the principles of sound policy suggest a particular idea that lies outside the Overton window, what is to be done? Shift the window. Since commonly held ideas, attitudes and presumptions frame what is politically possible and create the “window,” a change in the opinions held by politicians and the people in general will shift it. Move the window of what is politically possible and those policies previously impractical can become the next great popular and legislative rage.

Trump and Mick Mulvaney are attempting to do precisely this through the presidential budget proposal. Do they expect to see Congress sustain the dramatic cuts in domestic-policy agencies and the elimination of nearly two dozen of them? They would certainly like to see that done, but Mulvaney’s been around long enough to understand how this game works. Until now, these kinds of cuts and eliminations have been portrayed by the media as agenda items for conservatives and budget hawks on the fringes. Coverage of calls to eliminate the National Endowment for the Arts and the Corporation for Public Broadcasting, and to cut off UN funding, has been minimal and mainly dismissive. Suddenly, those ideas are now central to the current budget debate, along with deep cuts once considered to be unthinkable.

Republicans on Capitol Hill now have the room to object to some cuts and some of their depth even while pushing for cuts of somewhat lesser intensity and perhaps fewer eliminations. Those positions would have looked more extreme in the Overton window of 2016, but now it’s coming closer to the center. The Trump proposal reshapes the political battlefield and gives Republicans more room and more leverage to get what they want from the upcoming budget fight. For the White House, it’s a classic Art of the Deal “big ask,” forcing Congress as a whole to come towards his position in order to get a budget signed.

In other words, this isn’t a budget — it’s a political attack on the budgetary status quo. It’s a disruption to conventional wisdom about budgeting, which is a fulfillment of Trump’s mandate. Republicans are criticizing it because it’s designed for that purpose. The best advice for this budget is to take it seriously, and not literally.