By Jon Herskovitz

AUSTIN, Texas (Reuters) - Emboldened by Brexit, U.S. secessionists in Texas are keen to adopt the campaign tactics used to sway the British vote for leaving the European Union and are demanding "Texit" comes next.

The citizen-driven vote in Britain can be a model for Texas, which was an independent country from 1836 to 1845, and its $1.6 trillion a year economy would be among the 10 largest in the world, said Daniel Miller, president of the Texas Nationalist Movement.

"The Texas Nationalist Movement is formally calling on the Texas governor to support a similar vote for Texans," the group said on Friday. The office of Texas Governor Greg Abbott was not immediately available for comment.

The group, which claims about a quarter million supporters, failed earlier this year to place a vote on secession on the November ballot but aims to relaunch its campaign for the next election cycle in 2018, buoyed by the British vote, Miller said.

"Texit is in the air," he said.

Texit, for Texas exit, is a play on the British exit, or Brexit, and was trending on Twitter in the United States on Friday.

"Yee-haw! #Brexit shows how to get it done. Now we need a #Texit," tweeted user Phillip Paulson (@PaulsonPhillip).

Constitutional scholars, however, say a U.S. state cannot break away, but this has not stopped hundreds of secessionist schemes throughout the nation's history. No state has been formed by seceding from another since 1863, when West Virginia was created during the Civil War.

From Maine to Alaska, the bids to break away by groups often angry at taxation or what they see as an infringement of their liberties have been unsuccessful either due to the nearly impossible legal challenges or lack of support.

A 2014 Reuters/Ipsos poll showed nearly a quarter of Americans are open to their states leaving the union.

In Texas and other states, the Brexit vote came too late for U.S. secessionist to use it as a springboard to launch drives resulting in ballot measures for the November election.

But it did push the idea that if they can land a measure on the ballot for secession, they have a good chance to win over voters.

"We intend to mimic that process here in California by putting an independence referendum on the ballot so we can exercise our right to self-determination and vote to leave or remain part of the American Union," said Louis Marinelli, president of the secessionist group, the Yes California Independence Campaign.

VERMONT REPUBLIC?

The group, which opposes what it calls mass domestic surveillance and militarization of California’s local police departments, said the state has the resources to go it alone and doing so will be in the best interest of Californians.

Campaigns have been simmering for years in places like Hawaii and in New Hampshire, where the Free State Project has been looking to have 20,000 people move to the New England state and set up a colony of like-minded people opposed to big government.

Most movements are small and centered around a few leaders. A campaign for secession in Vermont called the Second Vermont Republic lost steam when its founder Thomas Naylor died in 2012. The group was pushing for a small, democratic, nonviolent and egalitarian state.

"Tom would have been happy," his widow Magdalena Naylor said of the Brexit vote.

(Additional reporting by Jim Forsyth in San Antonio; Editing by Cynthia Osterman)