Alhaji Mahamadou Abubakar's pronouncement comes after official campaigning ahead of the referendum ended Sunday.
Embattled President Tandja, whose second five-year term ends in December, wants to change the constitution to extend his rule for three more years.
But opposition parties sharply condemn the referendum and accuse Tandja of subverting the constitution, an action they describe as a coup d'état.
Chief supporter Alhaji Mahamadou Abubakar told VOA that Nigeriens will vote overwhelmingly in favor of President Tandja's term limit extension.
"Everybody is ready and everybody is happy to see that day… I'm very sure major people are ready… because I made my rounds and (came to the conclusion) that people are very, very ready," Abubakar said.
Abubakar said he is backing the president's term limit extension despite coming under enormous personal attacks.
"I am the one who started that… (Calling for term limit extension) without any help from any side. When I started, everybody thought I was crazy… but I am very happy," Abubakar said.
He said the will of the people forced the president to go ahead with Tuesday's referendum.
"Tandja is ready, why? Because he is following what the people like. He cannot say no because he is the president for the population (and) what the people like, he (Tandja) likes," he said.
Abubakar described the opposition as not having good intentions for the ordinary Nigerien.
"Niger's opposition, nobody has love for the country, nobody likes the country to go (forward). Everybody likes for their pocket, and they like to be big multi-billionaires. It is not to help the country, and it is not to help the poor people," Abubakar said.
He said President Tandja enjoys popular support because of his policies geared towards alleviating the suffering of the average Nigerien.
"Tandja is a very nice president with the poor people. And the constitution has given him right…so what the people like that is what the president will do," he said.
Abubakar said President Tandja should be allowed to finish the good works of rebuilding the country that he started.
But some political observers say Tandja's planned referendum has plunged the country in a deep political crisis. To hold the controversial poll, Tandja, has dissolved both parliament and the Constitutional Court.
The opposition has voiced outrage and is threatening to stage a coup and use all legal means to prevent the referendum.
The opposition has vowed to thwart the upcoming referendum despite alleged government arrest threats.
Published with the permission of Voice of America