TASHKENT, April 30 (Reuters) - Uzbekistan votes on constitutional amendments on Sunday that promise its citizens greater social protection in exchange for resetting President Shavkat Mirziyoyev's term count to zero, which could allow him to stay in power until 2040.

Mirziyoyev, 65, has been praised at home and abroad as a liberal reformer for abandoning the previous leadership's isolationist policies and police state approach.

And while Tashkent's Western partners are unlikely to approve of the attempt to extend presidential powers, Uzbekistan risks little given the West is seeking support from all ex-Soviet nations in its efforts to isolate Russia.

Although the current and the proposed new version of the constitution limit successive presidential terms to two, officials have said that if the revised constitution is adopted Mirziyoyev's term count would be reset to zero.

The reform also extends the presidential term to seven years from five, which could in theory allow Mirziyoyev to remain in charge of the country of 35 million people until 2040.

At the same time, the package of amendments proclaims Uzbekistan a "social state" with increased welfare obligations and allows non-farming land ownership.

It also abolishes the death penalty and establishes greater personal legal protection, for instance to a person's rights when they are detained by police, and the concept of habeas corpus, or protection against unlawful and indefinite imprisonment.

Some Uzbek commentators have called for more democratic principles to be included in the bill, and in stronger wording, but the general idea of reform - and extending presidential powers in particular - has met no opposition.

The referendum will be declared valid if over a half of Uzbekistan's 19.7 million voters participate. Preliminary vote results are expected on Monday.