Mark Prater, a fixture in GOP tax policymaking on Capitol Hill, is leaving his post as chief tax counsel for the Senate Finance Committee.

“Mark has played a vital role in every major tax debate in the last quarter century,” Finance Chairman Orrin G. Hatch announced Tuesday in a statement, noting Prater’s work on last year’s tax code overhaul, the Bush-era tax cuts and more. He joined the Finance Committee in January 1990. Tuesday was his last day with the panel.

“This experience, coupled with his encyclopedic knowledge of the tax code, has proved instrumental not only to the committee, but also to the conference as a whole as we ushered the passage of the largest tax rewrite in more than 30 years through Congress — we couldn’t have done it without him,” Hatch said.

Prater is also deputy staff director for the panel.

Republican Sen. Charles E. Grassley of Iowa, a former Finance chairman, once called the longtime staffer “the real kingmaker” on tax policy.

Democrats who have worked with him are also quick to praise Prater as a solid partner and valuable resource. When Congress set up the bipartisan “supercommittee” in 2011, hoping to strike a major deal on deficit reduction, Prater was named staff director by the panel’s Democratic and Republican co-chairmen.

“Mark has a well-earned reputation for being a workhorse who members of both parties have relied on,” supercommittee co-chairs Sen. Patty Murray, a Washington Democrat, and Rep. Jeb Hensarling, a Texas Republican, said in a statement at the time.

Earlier this year, Prater was awarded the 2018 “Pillar of Excellence” award by the nonpartisan Tax Council Policy Institute.

Prater’s is the latest in a series of high-profile departures from the Republican tax world now that the new law is firmly in place.

Hatch is retiring from the Senate after his term ends, and the House Ways and Means Committee saw several top policy and communications staffers leave the panel in recent months, including former staff director David Stewart. Brendan Dunn, the chief tax aide to Senate Majority Leader Mitch McConnell, starts a new job Thursday at lobbying firm Akin Gump Strauss Hauer & Feld.

Jennifer Acuna, senior tax counsel and policy adviser for the Finance Committee, will replace Prater as chief tax counsel. Hatch credited Acuna with spearheading the rewrite of international tax rules in last year’s overhaul. She previously worked for the House Ways and Means Committee as tax counsel.

Jeff Wrase, chief economist for the committee, will take over as deputy staff director.

Becky Cole, previously chief economist for the Budget Committee, will become the Finance panel’s policy director.

Oregon GOP tradition

A native of Portland, Oregon, Prater began his time on Capitol Hill when a strain of moderate Republicanism embodied by his home-state GOP senators Bob Packwood and Mark Hatfield was still in full bloom.

Republicans were in the minority in 1990 when Prater joined the Finance staff, as Congress and President George Bush began to unravel the 1986 tax code overhaul Packwood helped push through when he was Finance chairman.

The 1990 budget reconciliation law raised the top marginal tax rate from 28 percent to 31 percent and broke the “parity” that briefly existed between ordinary income and capital gains, while increasing an array of other taxes and breaking President George Bush’s “read my lips” pledge.

Nineteen Senate Republicans — including Packwood — and 47 House Republicans voted for the 1990 deal; that was the last time GOP lawmakers voted expressly to increase taxes. It birthed the anti-tax pledge pioneered by Americans for Tax Reform founder Grover Norquist.

Prater’s party endured another round of tax increases three years later at the hands of President Bill Clinton and Democratic majorities in both chambers. But in 1997, after Clinton’s party had taken a drubbing in the 1994 midterms, Congress passed and Clinton signed tax legislation that cut the capital gains rate from 28 percent to 20 percent, among other things.

The 1997 law also created the now ubiquitous Roth Individual Retirement Accounts, named for then-Finance Chairman William Roth of Delaware, which allow workers to contribute after-tax earnings and withdraw the funds tax-free upon retirement, including any capital appreciation over the years.

In a 2014 interview with Roll Call, Prater called the 1997 law one of his proudest achievements.

Prater helped popularize the term “tax relief” in Republican policy circles as a means of selling deficit-financed tax cuts to the public, amid Democratic opposition to “tax cuts for the rich.”

The GOP, under Grassley’s chairmanship at Finance and under Prater’s watchful eye, was off to the tax-cutting races with the election of George W. Bush, undoing Clinton’s 1993 tax increases in 2001 and enacting tax rate parity for dividends and capital gains at a low rate of 15 percent in 2003.

When the political pendulum swung back to the Democrats, Prater was forced to watch as the then-majority cleared President Barack Obama’s 2010 health care law. Obama again won a policy victory in late 2012, when he muscled through an increase in tax rates for upper-income households because the alternative was seeing all of the 2001 and 2003 Bush-era tax cuts expire.

Tragic loss

There were low points along the way for Prater, and then some.

The Finance GOP staff in 2016 tragically lost one of their own, tax counsel Jim Lyons, who collapsed at a charity basketball game. Prater had hired Lyons eight years earlier to be his heir apparent.

Prater was a constant presence at Lyons’ side during his final days, and delivered the eulogy at a memorial service filled to capacity with friends, family and those who worked alongside Lyons — known for his kindness, generosity, humor, quick wit and brilliant policy and political mind.

Prater finally got his shot to shape a far-reaching revamp of the tax code once President Donald Trump was seated in the Oval Office last year, having missed the 1986 window of opportunity by a few years. Various negotiations in the intervening decades failed to bear fruit, including during the supercommittee talks.

It wasn’t the bipartisan effort that Prater would have preferred, and it made the deficit situation worse than it would be otherwise, according to the Congressional Budget Office and Joint Committee on Taxation.

But the 2017 tax law achieved some objectives the GOP staffer had long sought — a lower, flatter rate structure with many deductions and carve-outs scrubbed from the code, and incentives for businesses to invest domestically rather than “invert” to an overseas jurisdiction.

Prater passed up numerous chances to join the K Street crowd for a bigger payday over the years. Those who know him have said he doesn’t seem like the type. But Prater also cut his teeth as a tax lawyer in private practice before moving to Capitol Hill, and countless businesses could undoubtedly benefit from his expertise on the new tax law.

One way or another, Prater seems likely to continue to play a role in the tax and fiscal policy debates to come.