WASHINGTON — The Supreme Court Monday rejected Arkansas’ effort to put an election-ballot brand on candidates who fail to support congressional term limits. The action may provide term limits opponents in Maine the ammunition they need to strike down a similar measure, known as the “scarlet letter” law.

The justices, without comment, let stand an Arkansas Supreme Court ruling that invalidated a ballot initiative similar to those approved by voters in eight other states, including Maine, in November.

Under the provision, elected officials whose efforts in behalf of term limits were deemed unsatisfactory would have had “scarlet letter” notations next to their names on Election Day. It would have stated: “DISREGARDED VOTER INSTRUCTION ON TERM LIMITS.”

The “scarlet letter” nickname for the law comes from the 1850 Nathaniel Hawthorne novel in which people convicted of adultery were forced to wear a scarlet “A.”

A lawsuit filed last month in U.S. District Court in Portland by the Maine Civil Liberties Union and the League of Women Voters of Maine seeks to strike down the law favored by 59 percent of voters in a statewide referendum last November.

Sally Sutton, executive director of the MCLU, said her group was pleased by the Supreme Court action, but still planned to press ahead with the legal challenge to the Maine law.

“We filed a challenge in federal court on Jan. 2. It is now in U.S. District Court in Bangor with Judge Morton Brody,” Sutton said.

The Supreme Court action “is a good indication that our position is correct,” she said. “We will keep going ahead with it until state officials concede that [the law] is invalid. We’re going to proceed with it until we get a final determination.”

Term limits opponent and Portland attorney David Soley said the court’s decision “provides powerful guidance to the court in Maine” and vindicates his position. “People have the right to vote for whoever they want, but the government doesn’t have the right to print statements next to a candidate’s name,” he said.

Attorney General Andrew Ketterer cautioned, however, that the Supreme Court action may not be the last word on term limits.

“The decision of the Supreme Court is not a decision on the merits,” said Ketterer. “I wouldn’t really read too much into it.”

John Michael of Auburn, who led the petition drive that resulted in the “scarlet letter” law in Maine, said Monday’s decision “means an extended legal battle in several states. Different states may have different opinions on these laws and I think the Supreme Court will eventually have to take the case.”

Michael pointed out that Monday’s action had no effect on the state’s term limits law for legislators and constitutional officers.

He sees the candidate-labeling law as a helpful tool, but not an essential one in the campaign for congressional term limits.

“What we have going for us is the people are on our side,” Michael said. “We’ll eventually get these guys.”

Rep. Thomas H. Allen is the only member of the Maine congressional delegation to oppose term limits.

Mark Sullivan, Allen’s press secretary, said Monday, “Tom thinks this is a good ruling. It makes sense. It doesn’t make for good government to put political opinions on the ballot.”

The nation’s highest court had dealt a similarly devastating blow to term-limits backers in 1995 when it ruled that states cannot limit service in Congress without amending the Constitution. Twenty-three states had taken such steps.

The court’s 1995 decision also said Congress cannot impose term limits for its own members by merely enacting a law.

The Arkansas measure called on the state’s legislators and members of Congress to do all within their power to win ratification of a proposed amendment limiting service to 12 years in the U.S. Senate and six years in the House.

The House rejected such a proposed amendment on Feb. 13, and the Senate is unlikely to resurrect it.

Similar propositions have won approval in Alaska, Colorado, Idaho, Maine, Missouri, Nebraska, Nevada and South Dakota.

Each measure requires those states’ congressional members to push for a vote that would send the proposed amendment to state legislatures for ratification.

Court challenges are being waged in Idaho, Maine, Missouri and Nebraska — and future challenges in the four other states are likely.

The Arkansas Supreme Court ruled that the measure adopted by its state’s voters violated the federal Constitution’s requirement that all amendment-making efforts originate in Congress or in the state legislatures.

That ruling was appealed by a group called Arkansas Term Limits and the state, represented by Attorney General Winston Bryant.

“It’s just a temporary setback,” Bryant said of Monday’s court action. “There’s a lot of popular support for term limits.”