We have some modest advice for Republicans regarding the tax bill unveiled last week – don’t screw this up.

Do the right thing. Do what you said you were going to do. Pass a bill that simplifies the tax code and gives relief to the middle class — everyone in the middle class.

Deliver on a bill that lowers taxes, the Holy Grail of modern Republican orthodoxy, and most other failures will be forgiven. Screw it up, and, well, maybe Lindsey Graham wasn’t far off when he said “it will be the end of the party as we know it.”

That might be an exaggeration, but it won’t be pretty. This is a pivotal moment for Republicans who control both houses of Congress and the White House. They need a win in the wake of their inability to pass a new health care law.

They need a win to prove they can get something done.

President Trump, in typical Trumpian bombast, has promised America a “big, beautiful Christmas present” in the form of a tax break. He assures us it will be “giant, massive, the biggest ever in our country.”

The rationale for simplifying the tax code and lowering some taxes is compelling.

The federal tax code has ballooned to nearly 74,000 pages. That’s about 185 times longer than it was in 1913, when the code was a mere 400 pages. That is obscene.

President Jimmy Carter called the code a “disgrace to the human race.” President Reagan called it a system of “endless confusion and resentment.” Yet the tax code grows each year with even more tax credits, deductions, exemptions and interpretations.

Republicans contend under their new plan, most Americans will be able to complete their taxes on a form the size of a postcard. That’s hard to believe, but something to shoot for.

The case for lowering the corporate tax rate is equally persuasive. We don’t have the highest corporate tax rate in the world, but our 35 percent rate is higher than many other industrialized nations.

In an increasingly global economy, that doesn’t make sense. U.S. companies need a competitive playing field. Other countries have already slashed their corporate tax rates. At the very least, we need a tax structure that doesn’t entice American businesses to move profits and operations to foreign countries just to avoid higher taxes.

Our sense is that Americans will support a tax cut proposal, even one that disproportionately benefits corporations and the wealthy, if all working class taxpayers get a break.

Most of us feel we pay too much in taxes. Most of us are willing to trade a higher national debt for lower taxes. That may not be prudent, but it is reality.

As Congress begins the mark-up process on the tax plan, which is only beginning to be evaluated and seriously analyzed, we remind our friends in Congress that the tax proposal was sold as a plan to reduce the federal tax burden on the middle class.

The president and other GOP leaders have given firm assurances that everyone in the middle class would realize lower taxes under the plan.

Already, some are contending that many working class households would actually see their tax bills rise in upcoming years as a result of the loss of some exemptions and the interplay of other credits and deductions.

That is unacceptable. While it is early in the markup process, it’s a good time to remind Congress that one sure-fire way to screw this up is to not deliver on that key promise.

There are always winners and losers in any new tax plan. But if it turns out that some of the losers are actually in the middle class, the GOP has failed.