Nachura, chairman of the House committee on constitutional amendments, said the House-commissioned survey, conducted from June 26 to July 3 involving 300 voters in Metro Manila, showed that 42 percent of respondents approved of Cha-cha.
The percentage result was an improvement over the results of two earlier nationwide surveys where Cha-cha got the nod of only about a third of respondents.
"We are seeing the turning of the tide of public opinion in favor of Charter amendments. This is absolutely a significant push for the movement to amend the Charter for it proves that more Filipinos are listening to us than those opposed to change," Nachura said.
Speaker Jose de Venecia, one of the main proponents of Cha-cha, said he was elated by the survey results and that the continuing struggle to change the structure of government "has not been in vain."
"The dramatic increase in the number of Filipinos who favor Charter amendments only proves that our efforts have not been in vain to change the political structure of government," he said.
"We have been campaigning for more than 10 years for a parliamentary system. We believe the change in the form of government will be one of the top solutions to our problem. It will end the politics of gridlock, reduce corruption, speed up the process of lawmaking and help reduce destructive and personality-oriented politics," de Venecia said.
The SWS survey, which was commissioned by Nachuras committee, showed a "fast rise" compared to previous findings on the level of public approval for Cha-cha, Nachura said during a press briefing at Maxs restaurant in the Quezon Memorial Circle.
In an earlier SWS nationwide survey conducted in December among 1,200 voters, only 28 percent of respondents approved of Cha-cha.
In another SWS survey conducted from May 28 to June 13 among 1,200 voters, only 30 percent favored Cha-cha.
But Nachura said the latest survey was "a major turning point" although the sample of respondents was smaller and the coverage limited to the Metro Manila area.
"This is a clear indication that respondents feel the need to have just one parliament to speed up the lawmaking process," he said.
In explaining the survey, the SWS told the Nachura committee that respondents are "closely divided among those favoring a constitutional convention (which leads by a tiny plurality) and a constituent assembly" when two modes of amending the charter are presented to them.
Forty-eight percent of respondents agreed to change the legislature from a bicameral to unicameral form.
Of those in favor of changing the legislature from bicameral to unicameral, 32 percent favored instituting amendments via constituent assembly while 41 percent favored a constitutional convention.
The survey also showed 34 percent agreed to change from a presidential to parliamentary government while 43 percent approved the creation of regional governments. Forty-five percent disagree with the proposal for a federal government.
Of those in favor of shifting to a parliamentary government, 41 percent favored a convention and 27 percent a constituent assembly but almost a third (32 percent) said either form of government would be "acceptable."
"We are absolutely encouraged by the latest results and we are absolutely certain more Filipinos will agree with us if we are able to reach them and explain the superiority of the constituent assembly over the convention," said Marietta Goco, convenor of the Coalition for Charter Change Now.