Democrats in the legislature said at the time that Allen’s veto power extended only to individual appropriations or written provisions linked to money.

So a key issue in the current case might be whether the Medicaid amendment stands alone in the budget, or whether it is considered tied to an appropriation.

Sen. William M. Stanley Jr., R-Franklin County, said Friday that he believes his amendment is “veto-proof.”

If McAuliffe and lawmakers are considering a court fight, timing also is an issue. Both sides want to sign off on the budget as soon as possible in order to tackle the projected revenue shortfall.

Last month Attorney General Mark R. Herring brought in A.E. Dick Howard of the University of Virginia, principal author of the 1971 rewrite of the state constitution, as a consultant on the budget impasse. Howard was one of three lawyers the assembly hired in the 1996 case.

Expanding Medicaid to about 400,000 Virginians through the federal health care law is a top goal of McAuliffe’s and was a major part of his platform during his gubernatorial campaign.

McAuliffe said in a statement Thursday night that when the budget reaches his desk he will “take the actions that I deem necessary, but this fight is far from over.”