Tim Eyman proposed a new initiative on Monday that would chop billions out of the state budget unless the Legislature moves ahead with a constitutional amendment requiring a two-thirds vote to approve new taxes.

The state Supreme Court ruled last year that requiring a two-thirds vote in the Legislature to raise taxes was unconstitutional and said only a constitutional amendment could put such a restriction in place.

Democrats, who control the House and the Governor’s Office, have not been interested in doing that. Changing the state constitution requires a two-thirds vote in both the House and Senate, and simple-majority approval by voters.

Voters first authorized the two-thirds requirement in 1993. They reimposed it in 1998, 2007 and 2010 and reaffirmed it in 2012, at least in part because of lawmakers’ penchant for suspending the requirement to raise more revenue.

Eyman, who makes his living sponsoring initiatives, successfully sponsored measures in the past to keep the two-thirds requirement on the books — until the Supreme Court ruling.

Eyman’s new proposal would reduce the state sales tax by a penny, cutting the state portion from 6.5 to 5.5 percent. That would represent about $1 billion a year in lost revenue. The Legislature could prevent the tax cut by putting a two-thirds constitutional amendment on the ballot.

Eyman is aiming the initiative for the November ballot but will need to get at least 246,372 valid signatures for it to qualify.

Under state law, it takes a two-thirds vote of the Legislature to amend an initiative in the first two years after voters approve it. After two years, lawmakers can change voter-approved initiatives with a simple-majority vote.

Eyman said that while state lawmakers might call his proposed initiative blackmail, “we would say we’re giving them a strong financial incentive to let the people vote.”

Andrew Garber: 360-236-8268 or agarber@seattletimes.com.