Virginia Gov. Terry McAuliffe and the GOP legislature are arguing over the status of his veto of budget language blocking Medicaid expansion. (Andre Teague/Associated Press)

Gov. Terry McAuliffe and the Republican legislature have escalated a long-running fight over whether a handful of his vetoes are valid — a battle that could determine whether the Democrat is able to pull off his marquee campaign pledge to expand Medicaid before leaving office in January.

McAuliffe on Friday issued an executive order directing state agencies to recognize the state budget as he sees it — including five vetoes he made to various parts of the two-year spending plan.

One of those vetoes, issued a year ago, rejects language that the General Assembly had inserted to prevent him from expanding Medicaid under the Affordable Care Act without its permission.

Republicans said at the time that the governor lacked the power to strike that language, known as the “Stanley Amendment” for the legislator who authored it, state Sen. William M. Stanley Jr. (R-Franklin). The House Clerk’s Office, which prints the final laws, ignored the veto, as it had when he vetoed similar language in the budget passed in 2014.

While McAuliffe and the legislature have sniped in the past over the disputed vetoes, the sharply worded executive order — which accused the House clerk of “a profound abuse of authority” — and the furious GOP response — which blasted the move as a stunt meant to advance McAuliffe’s potential 2020 presidential bid — suggested the stakes were higher than ever.

Republicans saw the order as a sign that McAuliffe was laying the groundwork to circumvent a General Assembly staunchly opposed to expansion. The governor’s spokesman confirmed that he was, once again, exploring that possibility.

“The governor is committed to this,” McAuliffe spokesman Brian Coy said. “We’ve never stopped looking for a way to bring these taxpayer dollars home. There are obstacles that we are working to overcome there, but we don’t view the Stanley Amendment to be one of them.”

McAuliffe won the governorship in 2013 on a promise to expand the federal-state health-care program under the Affordable Care Act. He said expansion would provide care to 400,000 uninsured Virginians, boost the state economy and create tens of thousands of health-industry jobs.

Republicans have opposed expanding what they say is a wasteful program and questioned whether Washington can afford to keep its promise to foot most of the bill — potentially leaving Virginia on the hook for the $2 billion-a-year tab.

The timing of the order surprised some, given McAuliffe’s diminished push for expansion in recent years and the ACA’s imperiled status in Washington, where the House of Representatives has passed a plan to repeal key parts of the law. McAuliffe took Virginia to the brink of a state government shutdown over the issue in his freshman year but has since focused on economic development, a goal with bipartisan appeal.

Should McAuliffe pull it off, expansion would substantially bolster the legacy of a politician mentioned as a potential Democratic contender for president in 2020. McAuliffe has said he has not ruled out a run but will remained focused on his job as governor until his term is over.

“Frustrated by my successful veto of 120 of their bills, General Assembly members have resorted to legislating through the budget, using the appropriations power to change existing law in Virginia,” McAuliffe said in his order. “This is an abuse of legislative power and a violation of the Constitution of Virginia. Moreover, the House Clerk’s refusal to publish actions taken by the Governor is a profound abuse of authority, purporting to endow an unelected ministerial officer with some extra-constitutional power to override the Governor’s vetoes based on his own legal opinions.”

House Clerk G. Paul Nardo declined to comment.

“The clerk’s actions were consistent with past practice under both Republican and Democrat speakers with both Republican and Democrat governors over the past 21 years,” House Speaker William J. Howell (R-Stafford) said in a written statement. “The [state] Supreme Court is abundantly clear about the limits of the governor’s line-item veto authority and there is no doubt Governor McAuliffe exceeded that authority.”

Senate Majority Leader Thomas K. Norment Jr. (R-James City) called McAuliffe’s order a “case study in executive arrogance” and suggested that it “amounts to a thinly veiled press release to promote his 2020 presidential ambitions.”

Virginia’s governor enjoys a line-item veto, but Republicans note that state Supreme Court rulings require that he strike a budget item in its entirety when he vetoes it and that he lacks the power to strike out conditions or restrictions that apply to an item.

In 2014, Republicans contended that McAuliffe could not veto the Stanley Amendment without striking the entire Medi­caid program. McAuliffe’s office disagreed but never challenged the House clerk’s decision to leave his veto out of the final law.

Last year, Republicans structured the anti-expansion amendment to apply to the entire state budget, not just the Medicaid program. McAuliffe contends that approach unconstitutionally limits his line-item authority.

The difference of opinion could be the basis for a legal challenge by Republicans, particularly if McAuliffe moves ahead with expansion.