Mr Prompong said Pheu Thai MPs will meet people in different areas to explain the content of the planned amnesty law and prevent them from being misled into believing that its sole purpose was to benefit a few individuals.
"The amnesty law will be for the benefit of the people. It will cover all sides because it wants to create reconciliation and does not want to discriminate against anyone.
"Pheu Thai's legal team has thoroughly studied the law and it is not unconstitutional as the Democrat Party claims," Mr Prompong said.
The Democrat Party will lead a march of opponents to the government's blanket amnesty bill from Samsen railway station across Bangkok Monday in a stepped up campaign against the law change.
Democrat heavyweight Suthep Thaugsuban declined to identify the destinations of the march but a well-placed party source said the move, which will begin at 10am (0300 GMT), is aimed at paralysing traffic in the capital to press for an end to the bill.
Mr Prompong said core members of the Democrats have held an anti-amnesty rally near Bangkok's Samsen railway station since Friday because they had a political agenda. They want to topple the government rather than seek justice as they claim, he said.
Mr Prompong called on the Democrats to end their protest so people can mourn the loss of His Holiness the Supreme Patriarch, Somdet Phra Nyanasamvara Suvaddhana Mahathera. Thailand's economic and tourism sectors could be affected if the rally is prolonged, he added.
Pheu Thai also planned to take legal action against Somchai Sawaengkarn, an appointed senator, who accused the party of being controlled by former prime minister Thaksin Shinawatra, brother of current premier Yingluck Shinawatra, he said.
Senate Speaker Nikom Wairatpanich said the Senate is scheduled to deliberate the Amnesty Bill in the first reading on Nov 11.
Mr Nikom said the Senate will not put on the agenda any pieces of legislation for consideration on Nov 8 because on that day a number of senators would still be abroad.
After it passes the first reading, a committee will be set up to scrutinise it. The scrutiny period is for 60 days and can be extended another 30 days if necessary, he said.
The speaker said if the Senate disagreed with the bill, it would be returned to the House of Representatives for reconsideration.
Several groups, including the low-key and obscure ratchasakuls (descendants of members of the royal family) and numerous individuals have begun intensive campaigns against the bill.
Alongkorn Ponlaboot, deputy leader of the Democrat Party, said the Democrats on Monday will launch their nationwide campaign against the bill, starting with Phetchaburi province.
Mr Alongkorn said the campaign is part of the Democrat Party's fight inside and outside of parliament to persuade the people to join forces to stop the government from using its majority in the House to destroy the country.
The Phetchaburi forum will be held Monday. Similar forums will then be held in Trat, Chon Buri and other provinces throughout the country.
Mr Alongkorn called for the Senate to reject the Amnesty Bill.
A petition will also be filed with the Constitution Court to rule on the constutionality of the bill.
The party will also file for a no-confidence debate against the government, which has damaged the country's credibility, he said, particularly its ongoing push for the passage of the Amnesty Bill to whitewash corrupt practices in violation of a United Nations convention against corruption.
Mr Alongkorn said his party will fight outside parliament within the scope of the constitution.
On the academic front, a total of 578 lecturers of Thammasat University have issued an open letter opposing the Amnesty Bill and called on the Senate to reject it.
The letter said the bill offering a blanket amnesty would benefit not only people involved in the past political violence and expression of opinion but also other wrongdoings including corrupt practices by holders of political positions.
This is against the rule of law and the principle of amnesty, which requires clear reasoning and a scope of coverage.
The bill will not only cause law violators, particular in corruption cases, to disregard the law but will also not do away with political conflict as claimed by its advocates.
For those reasons, the lecturers said, they had to oppose the bill. They called for the Senate to show responsibility towards Thai society by voting against the bill which they said will lead to serious conflicts.
As for the general public, 87.2% of the respondents in a survey conducted by Abac Poll think the Amnesty Bill is intended to absolve former premier Thaksin of wrongdoing, not to bring about reconciliation.
The remaining 12.8% believed it was for reconciliation.
The poll was conducted on 1,198 people aged 18 and up in Bangkok and other major cities between Oct 29 and Nov 2.