TBILISI (Reuters) - Georgian President Giorgi Margvelashvili on Friday reluctantly signed into law a new constitution that will do away with direct election for president and switch to a system of proportional representation in parliament.

Margvelashvili, who unsuccessfully tried to veto the draft bill, said it was personally difficult for him to sign the document, but he did so in the interests of stability in the country which straddles an energy supply route to Europe and is an arena of strategic rivalry between Russia and the West.

“Considering the country’s internal and external challenges and the fact that we should do everything to avoid possible causes of detribalization, I am signing this document,” Margvelashvili said in a statement.

Margvelashvili had originally sent the draft back to parliament with his objections which included opposing a call for an end to direct elections for president. But parliament overturned his veto.

Margvelashvili, who was elected in 2013 for a five-year term, criticized the ruling Georgian Dream party for adopting the constitution without a consensus with other political forces in the ex-Soviet country.

“It has been obvious since the very first day (of the constitutional reform process) that the ruling party aimed to adopt a one-party constitution,” he said.

The next presidential election in Georgia is to be held in 2018 and it is not clear whether Margvelashvili, who is at odds with the ruling party on several issues, will stand again.

MPs from the Georgian Dream said the constitutional reform process set a new constitutional tradition and culture in Georgia.

“The amendments were introduced not to strengthen the ruling party’s political positions, but ... to strengthen democracy in Georgia,” Irakli Kobakhidze, a parliamentary speaker said.

The new constitution will enter into force following the next presidential election next year.