If Congress doesn’t approve the spending cuts in the “rescissions” package proposed Tuesday by President Trump, it will be a dereliction of duty and a display of political cowardice.

These spending cuts ought to be considered nearly child’s play, and they should be the least Congress can do to show tiny evidence of fiscal sanity amid an otherwise outrageous spending spree.

First, what exactly is a “rescission”? In federal budgetary parlance, it is the withdrawal of spending authority for funds already appropriated by law, but not yet actually spent by executive agencies.

For example, if Congress passes a law appropriating $12 billion a year for Agency X, payable in equal monthly installments, and the fiscal year is half finished, it means $6 billion of the $12 billion authority remains unspent. A new law to rescind that $6 billion, passed by Congress and signed by the president, would save the taxpayers that amount.

By federal law, there are two paths to rescinding appropriations. Trump has offered Congress the easier one.

In the hard version, Congress itself initiates the process. The rescissions bill in that case is subject to ordinary parliamentary rules, meaning a 41-vote minority of the 100-person Senate can kill it via a filibuster . Plus, it needs approval from a president who did not propose the cuts in the first place.

The easy version occurs when the president uses statutory authority to send a rescissions request to Congress. Under this scenario, both chambers of Congress can pass the cuts with bare majorities, without threat of a filibuster. Obviously, it is far easier to secure 51 votes than 60.

On Tuesday, Trump identified some $15 billion that (in most cases) is likely not to be spent anyway, and asked Congress to rescind those funds. For example, there is a $2 billion contingency fund for states, but states rarely meet the “contingent” terms. There’s another $5 billion technically appropriated for a children’s health program that the program never spends .

Eliminating the theoretical possibility of spending these funds should be easy. The only reason Congress likes to keep these theoretical spending possibilities on the books is so, when they want to add unexpected spending in some other areas before the year is out, they can claim to “offset” that new spending by then (and only then) cutting these theoretical funds. Thus – Abracadabra! – they show no additions, on paper, to the deficit.

It’s a shell game. Trump proposes to take away Congress’ shells. If these theoretical funds are taken away now, they can’t be used to hide more profligacy later.

Still, eliminating this spending authority takes few discernible funds directly away from any actual human beings. And, since only 51 Senate votes are required to do so, and the president’s party holds 51 Senate seats, this should be light legislative work – especially since Congress just spent an additional $63 billion (!) on domestic discretionary functions this spring. That $63 billion, which remains untouched here, should easily obviate the need for even more “unexpected” spending later this year.

In total, the $15 billion represents less than 2.5 percent of the more than $600 billion domestic discretionary spending previously approved.

Compare that to the second biggest rescission package of the modern (post-Nixon) budgetary era. I was press secretary at the House Appropriations Committee in 1995 when we rescinded more than $16 billion from what had been just a $250 billion domestic discretionary budget. That was a 6.4 percent cut, meaning, in percentage terms, more than 2.5 times larger than the one Trump is requesting.

And in 1995, Congress initiated the rescissions. We couldn’t pass them with just 51 Senate votes; we needed 60 (and got 61, including eight Democrats ). I saw firsthand the months of heavy lifting Republican leaders did, both in substance and in political salesmanship, as President Bill Clinton and a largely hostile media sniped at us at every step, accusing Republicans of heartlessness.

Unlike in 1995, this time the president is fully supportive, and only 51 votes are required. If Congress could muster 60 Senate votes against a sniping president for cuts 2.5 times the size of Trump’s request, why can’t it muster a mere 51 votes, with the support of the president, for this much smaller package – especially when, unlike in 1995, almost all the rescissions will come merely from merely theoretical accounts?

Even the 1995 effort pales in comparison to what President Ronald Reagan did in 1981 and 1982, his first year in office. In 1981, he pushed through Congress $10.9 billion in rescissions (6.4 percent of total domestic appropriations) and further secured another $4.35 billion in rescissions in 1982. He did this when the opposing Democrats held a 243-192 majority in the House!

And this was during a recession, when politicians usually like to boost spending. Today, Trump is merely trying to trim the edges of a massive spending increase, even though the economy is at full employment and spending cuts should therefore be easier to achieve.

If Senate Majority Leader Mitch McConnell and his troops can’t accomplish less than half of what the Reagan- and Clinton-era Congresses did, under far easier circumstances, they are to fiscal conservatism what Clinton and Trump are to marital fidelity.

Quin Hillyer (@QuinHillyer) is a contributor to the Washington Examiner's Beltway Confidential blog. He is a former associate editorial page editor for the Washington Examiner, and is the author of Mad Jones, Heretic, a satirical literary novel published in the fall of 2017.