If completed, the order -- the first foreign sale for the Lakota -- is worth about $77 million, a notice posted on the website of the U.S. Defense Security Cooperation Agency said.
The agency notified Congress of the proposed sale, which hasn't been finalized and may not go ahead.
Thailand is considered a friendly country whose security is in the interest of the United States, the agency said.
"This proposed sale will contribute to Thailand's goal to upgrade and modernize its military forces with a new light utility helicopter capable of meeting requirements for rotary-wing transportation, while further enhancing greater interoperability between Thailand the U.S. and among other allies," the notice said.
"Thailand will have no difficulty absorbing these helicopters into its armed forces."
The principal contractor for the sale, including associated equipment, training and support, will be the American Eurocopter division of EADS North America, in Herndon, Va.
But the Lakota is manufactured by American Eurocopter in Columbus, Miss., by a 300-person workforce that is more than 50 percent U.S. military veterans.
The twin-engine, single rotor Lakota UH-72 is a militarized version of the Eurocopter EC145.
The U.S. Army chose the Lakota as its light utility helicopter in 2006 to replace its old UH-1H/V and OH-58A/C helicopters. About 260 of the 345 ordered have been delivered and are used by the Army and Army National Guard for search-and-rescue operations, as well as security and medical evacuation duties.
The rest of the Army order is in doubt after defense budget cuts.
Eurocopter said U.S. Reps. Joe Barton and Marc Veasey joined leaders of American Eurocopter, EADS North America and Turbomeca USA at a rally this month to call on Congress to restore funding for the Lakota in the Fiscal Year 2014 budget.
The rally took place at EADS North America's American Eurocopter facility in Grand Prairie, Texas, where more than 600 Texans work.
American Eurocopter in Grande Prairie performs Lakota modifications, and upgrades and trains Lakota pilots and maintenance engineers from the Army, Army National Guard and Navy.
Notification of the proposed sale comes after the United States and Thailand renewed their 50-year military ties during a November visit to Bangkok by then-U.S. Defense Secretary Leon Panetta.
At the time, Voice of America reported Thai Defense Minister Sukampol Suwannathat as saying the agreement didn't create new initiatives or privileges between the two countries.
Panetta said the pact was aimed at confronting the new challenges from natural and man-made disasters as well as maritime security issues.
Panetta said the agreement will ensure "even stronger military-to-military ties as we adapt to the shared threats and challenges that we will face together in this region and in the future"
Voice of America quoted Panitan Wattanayagorn, a political scientist at Thailand's Chulalongkorn University, as saying the United States is refocusing on Asia at a time when China is growing its commercial and military ties with Thailand.
"It is quite challenging for Thailand to make sure that she doesn't move too much into the U.S. orbit at the same time continue to engage with more activities, especially in the security area, with the Chinese in the years to come, Panitan said.
"And that has to be kept up in order to make sure that the Chinese don't feel left out."
Panitan also said China has been invited with the U.S. and Thai military in annual exercises in Thailand known as Cobra Gold.