Nouakchott - A contentious amendment to Mauritania's constitution, which would abolish the Senate and change the national flag, will be put to a referendum "as quickly as possible," the president said Wednesday.The proposal to modify the constitution, which has been in force since 1991, was approved by lawmakers in the lower house of the west African Islamic republic but rejected by 33 out of 56 senators earlier this month."Due to this rejection, we have arrived at an impasse. But there is one way out: we will hold a referendum," said President Mohamed Ould Abdel Aziz at a press conference late Wednesday.The amendment, which would see the Senate replaced by regional councils, needed to be passed by both lower and upper houses to become law.The government has a majority in both chambers, but 24 ruling party senators voted against the measure, highlighting what the president said was a "dysfunction in our democracy"."We cannot allow 33 senators who voted against these amendments to hold the whole country hostage," he said, adding that "an exit exists, which is to go straight to a popular referendum."He said he could not give an exact date for the referendum poll, but said it would be organised "as quickly as possible."Under the amendment, those who fought for freedom from colonial master France would be represented on a new flag by a red band at the top and bottom of the country's green national banner, representing blood spilt for their nation.Mauritania won independence in 1960.The current green flag with a crescent and star symbolises the importance of Islam in the conservative republic, but lawmakers in the lower house from the ruling majority felt the nation's independence struggle was not adequately represented.