A protester places a peace sign on a defaced poster of Thai Army Chief Gen. Prayuth Chan-ocha during an anti-coup demonstration in Bangkok, Thailand Sunday, June 1, 2014. (Wason Wanichakorn/AP)

NINE MONTHS after staging a coup against a democratically elected government, Thailand’s military has little to show for it. The economy is stagnant, one of the worst performing in Asia. The national “reconciliation” the generals promised is nowhere to be seen: There are hundreds of political prisoners, and a criminal prosecution of ousted prime minister Yingluck Shinawatra is underway. Martial law remains in effect, making it illegal to hold any gathering without permission and crippling free expression.

Junta leader Prayuth Chan-ocha lamely protests that, unlike the military-backed regime of Egypt, his has not killed anyone. But given his reactionary plan to permanently hobble democracy, even that dubious distinction may not endure much longer.

The army is attempting to accomplish something it has failed at twice before: a political system that eliminates the influence of the Shinawatra family, which has won every election in Thailand since 2001. Thaksin Shinawatra, the family’s exiled leader, gained wide support among the rural poor with a populist program that infuriates the country’s traditional elite, including the military leadership.

Mr. Thaksin was guilty of authoritarian abuses while in office, and some of the policies he favored were ill-advised. But the ouster of three elected governments since 2006 has succeeded only in entrenching his support. Thai analysts believe that, if a free election were held now, Ms. Yingluck or another family nominee would win again.

Knowing that, Mr. Prayuth has delayed elections despite a promise that his regime would last only a year. But the generals have had trouble restoring relations with Thailand’s closest allies, including the United States, where a law mandated the shutdown of military aid and training programs after the coup. So during a visit to Tokyo this month, Mr. Prayuth pledged that an election would be held at the end of this year or in early 2016 — on the generals’ terms.

The military plan envisions a rewrite of Thailand’s constitution without a referendum to approve the result. The political system would be tilted, with reserved seats in parliament for the military and its supporters and tight controls on parties. The election itself would be held under martial law, making it impossible for parties or candidates to campaign freely.

The junta appears to hope it can return Thailand to the 1980s, when sham elections were followed by the installation of governments headed by generals. But Thailand has changed since then: An election held on the military’s plan could prompt Thais to take to the streets or turn to violence.

It should also be unacceptable to the United States. The Obama administration missed an important opportunity to use its leverage in Thailand when it went ahead with annual military exercises this month that are an important source of prestige for the generals. Its budget for next year proposes new military assistance for Thailand, though that should not be possible by law unless the country returns to democracy.

Mr. Prayuth should get the message that in the absence of meaningful steps, starting with the lifting of martial law, the Thai military will lose its relationship with the United States, including future exercises. If the Obama administration is unwilling to act, Congress should step in.