Sixteen of the erstwhile Roco supporters went to Malacañang Thursday night to make official their show of support while seven others who could not make it to Manila called ahead.
They described the President as "the best and most qualified to lead the nation through this difficult period."
Former lawmaker Luz Bakunawa said they sympathize with Roco, who returned this week from cancer treatment in the US.
But Bakunawa said it would be a "disservice to the nation" if they stayed with Roco and "did not choose the most qualified candidate."
"We made this declaration of support for President Arroyo in the interest of the nation. We were not approached by the administration. We offered our leadership for a common cause after deep consideration of present realities and our duty to the people," she said.
The erstwhile Roco supporters emphasized that voting for the former education secretary, whose rating dipped following his sudden departure for the US, would be tantamount to supporting movie star Fernando Poe Jr. of the Koalisyon ng Nagkakaisang Pilipino (KNP).
Poe, a high school dropout with no experience in government service, is riding on his popularity for a shot at the presidency.
"We feel that the same ideals we have been fighting for under our previous alliance are comprehensively carried in the platform of President Arroyo, especially the drive for universal free education," they said.
Former congressman Gualberto Lumauig said former Roco supporters — all heads of provincial organizations who were campaigning for Roco — shifted support to Mrs. Arroyo "entirely of our own volition and in the best interest of the nation."
"We call on our supporters to follow the lead of President Arroyo in uniting the nation and in fighting for change in the lives of the average Filipino," Lumauig said.
The lawmaker-supporters shifted their support to Mrs. Arroyo last April 23 while Roco was in the US on medical leave from the campaign.
They said their declaration of support is "in the name of national interest."
"We felt it is our patriotic duty to do so and state unequivocally that we do not support and will never be a part of the ongoing efforts of some Alyansa leader to seek a merger with other parties," said the manifesto signed by Lumauig and Rodolfo Tingzon.
They clarified they have nothing against Roco even as they expressed "sadness" over his medical condition. They said the mutual friendship remains and "we will pray for his full recovery."
"Our prevent prayers for his full recovery are with him. We cherish his friendship and share his deep concern about our country’s future," they said.
Lumauig said they decided to make public their support for Mrs. Arroyo "to end political intrigues and speculations."
The group said 10 Roco supporters had earlier declared their support for Mrs. Arroyo "even before Roco disclosed his ailment."
The decision to go over to Mrs. Arroyo’s camp was made during a meeting with other supporters at the Hotel Intercontinental last April 18.