President Donald Trump speaks about the passage of tax reform legislation on the South Lawn of the White House in Washington, DC, December 20, 2017.

The business model of the modern Republican Party does not produce real-world budget discipline. So today, GOP lawmakers turn to make-believe.

Within the last four months, the Republican president and party leaders in Congress took two actions that dramatically expand federal deficits. On a party-line vote, they cut taxes by $150 billion a year, then increased spending by $150 billion a year in cooperation with Democrats.

Now, as the Congressional Budget Office projects the return of $1 trillion annual deficits, congressional Republicans plan a gesture for constituents alarmed by rising debt. The House will vote on Thursday on a constitutional amendment requiring lawmakers to balance the federal budget.

The amendment lacks enough support to pass. Nor would GOP lawmakers want it to, since they have demonstrated unwillingness to make the policy choices the amendment would require.

In a second gesture, the White House is preparing to ask Congress to rescind some of the spending increases that Trump signed weeks ago. Bipartisan opposition from lawmakers who just affirmed them with their votes makes it unlikely such a proposal can pass.

Evidence suggests that gestures are the best the 21st century GOP can do. Decades of evolution have produced overlapping but disparate Republican segments whose priorities consistently drive deficits up.

Backers of supply-side economics dominate Republican tax policy. Urged on by GOP donors on Wall Street and in executive suites, they press continually to cut taxes.

Advocates of limited government welcome the resulting reduction of federal revenue. They want Washington to do less.

But proponents of strengthening America's military posture want more, so they pursue larger and larger Pentagon budgets. And older, working-class whites who disdain Wall Street and depend on government programs increasingly define the GOP voting base.

Specifically, those voters want to protect their benefits under Social Security and Medicare, both now ballooning as the massive baby boom generation retires. Conservative ideologues opposed those programs from their inception but have failed to roll them back.

No Republican faction openly disavows deficit reduction. But when President George W. Bush sought to fundamentally restructure Social Security in 2005, a Congress controlled by fellow Republicans declined.

In winning the presidency two years ago, Trump promised not to touch Social Security or Medicare benefits.

House Speaker Paul Ryan keeps exhorting his colleagues to curb them but hasn't succeeded, and on Wednesday, he announced his retirement.

The GOP has forced cuts to the narrow slice of the budget that finances other domestic spending, recently through the 2011 budget sequestration law. In practice, however, Ryan and other Republicans found those constraints too severe to sustain and acquiesced in Democratic attempts to relax them.

The central difference between the parties on budget discipline is that Democrats, while backing higher spending, have also backed higher taxes to finance it. Republicans keep supporting tax cuts even while failing to shrink spending.

The result: since Ronald Reagan entered the White House in 1981, all three Republican presidents before Trump left office with higher federal deficits than they inherited. One Democratic president (Bill Clinton) departed with a budget surplus; the other (Barack Obama) saw the deficit decline by two-thirds as a share of the economy.

That record has not deterred Republican claims that their policies will eventually reduce red ink. Last fall, the Trump administration insisted its tax cut would stimulate enough economic activity to boost annual growth to 2.9 percent over the next 10 years.

"Not only will this plan pay for itself," Treasury Secretary Steven Mnuchin predicted, "but it will pay down debt."

The CBO concluded this week that Mnuchin's forecast is a fantasy.

Its report projects annual economic growth of 1.9 percent over 10 years — mirroring the long-run outlook from before the tax cut passed. It projects the deficit growing from $665 billion in Trump's first year in office to $1 trillion in his fourth.

It envisions the national debt rising by $1.5 trillion above previous projections to reach $27 trillion by 2027.

When he backed the tax cut, retiring GOP Sen. Bob Corker cited his belief that it would not increase the budget deficit. After this week's CBO report, Corker fretted, "If it ends up costing what has been laid out here, it could well be one of the worst votes I've made."

Corker's House colleagues need not fear the same from their balanced-budget amendment vote Thursday. It won't change the deficit by even a single dollar.