As the Senate debates tax cuts this week, wavering Republicans face three fundamental realities about President Donald Trump's top legislative priority.
It would only modestly boost economic growth.
It would significantly increase the national debt.
It would give the most money to the richest Americans.
A flurry of published analyses in recent days has obscured their agreement on these core conclusions about the House and Senate tax bills. Economists from different points on the political spectrum disagree only about the magnitude of those changes.
Start with economic growth, the linchpin of arguments by the White House and Republican leaders.
The most generous estimate comes from the conservative Tax Foundation, which uses an aggressive form of "dynamic scoring" to measure the effect of tax changes on economic activity. Compared with other analyses, it assumes a stronger business response to lower taxes and a weaker drag on growth from higher debt.
Even so, the foundation's forecasts fall far below White House claims of 3 percent or more annual growth. Under the House bill, it projects the economy won't reach 3 percent growth in even a single year by 2027; under the Senate bill, only in 2018.
Overall, the foundation projects the economy in 2027 would be larger by 3 percent under the House bill and 3.7 percent under the Senate bill. Other forecasters envision much smaller boosts.
The Penn-Wharton model, directed by a former Bush administration economist, says the economy would be less than 1 percentage point larger by 2027 under either bill. The Tax Policy Center, whose staff includes some veterans of Democratic administrations, says the House bill would boost the economy by just one-third of a percentage point.
That matches the tempered expectations of Wall Street forecasters. In a survey of top economists by the University of Chicago's business school, only 2 percent agreed that the GOP tax cuts would substantially boost the economy by 2027; 51 percent disagreed.
The White House insists tax cuts will generate so much growth and tax revenue that deficits won't rise at all. But the consensus from others that they will rise makes the administration's claim sound like a late-night infomercial.
Penn-Wharton's dynamic analysis pegs higher 10-year deficits under the House bill of at least $1.5 trillion; the Tax Policy Center estimates $1.2 trillion. The Tax Foundation's dynamic analysis says the House and Senate bills will hike debt by $1 trillion and $516 billion, respectively.
Congress' Joint Committee on Taxation, the official bipartisan scorekeeper that did not employ dynamic analysis, says each would increase deficits by $1.4 trillion. In the University of Chicago survey, 88 percent of economists agreed that federal debt would be substantially higher as a share of the economy by 2027.
Such broad agreement poses a particular problem in the Senate. One potential swing vote, Sen. Bob Corker of Tennessee, has vowed to oppose tax cuts if he believes they increase debt after accounting for growth.
Nor do analysts disagree on who benefits most. The White House and GOP leaders insist they designed a middle-class tax cut, but economists agree the richest would benefit most.
Under the Senate bill, the Tax Policy Center finds the top-earning 1 percent of Americans would receive 61.8 percent of reduced taxes by 2027. Two-thirds of middle-income Americans, and half of taxpayers overall, would face a tax hike.
Under the House bill, Penn-Wharton projects the top 1 percent would reap 53 percent of all tax cuts by then. The Joint Tax Committee says $1 million earners would see their effective tax rates fall the most under both bills.
The Tax Foundation's "static" analysis yields similar findings. It uses a conventional assumption that 75 percent of corporate tax cuts go to business owners, while 25 percent go to workers.
The foundation's "dynamic" estimates flip those proportions, stipulating that workers get 70 percent and owners just 30 percent. Using that assumption, the Tax Foundation finds that under both bills after-tax incomes for the richest 1 percent would rise by a slightly smaller percentage than for Americans overall by 2027.
Yet even under that estimate, the most affluent make out best. Under both bills, the foundation says, the richest 1 percent would receive 15 percent of all reduced taxes by 2027; the most affluent 20 percent would get more than the bottom 80 percent combined.
Pitted against these realities, and polls showing public resistance, are warnings from GOP leaders and donors that failure on tax cuts guarantees calamity in 2018 elections. On the Senate floor, a half-dozen undecided Republicans have to decide which forces matter most.