The United Thai Nation (UTN) Party now hopes to win around 100 seats in parliament in the next general election, following Prime Minister Prayut Chan-o-cha's confirmation that he will join the party, according to Akanat Promphan, its secretary-general.
Gen Prayut's move, confirmed on Friday, will give the newly established party a popularity boost among prospective candidates in the polls, political pundits say.
Earlier rumours that about 40 key and former MPs from other parties would defect to the UTN proved largely true, said Mr Akanat.
Now that Gen Prayut has made it clear he will become the party's prime ministerial candidate, the number of frontrunners joining its ranks is expected to rise, he said.
More big names who are not MPs but who play key roles in local administrative organisations, such as the president of a provincial administrative organisation, may have an even better chance of winning than former MPs, he added.
"We have more than a hundred of these frontrunners, meaning we have enough prospective candidates to field in every region," Mr Akanat said.
Asked how many seats the UTN expects to win, he put the number at close to a hundred.
Yet it remains to be seen whether the UTN will be able to lead the formation of a new government next May, he said.
"If everything goes as expected, we will have quite a high number of MPs and we will likely be able to lead the formation of the government," he said.
Asked whether the UTN and the ruling Palang Pracharath Party (PPRP) would form an alliance after the next election, Mr Akanat said he saw no reason why not.
The UTN would be willing to work with any political party as long as their political ideologies corresponded to its own, he said, in response to a question as to whether the UTN would be prepared to work with the main opposition Pheu Thai Party.
The UTN is seen by many as a potential close ally of the yellow-shirt People's Alliance for Democracy (PAD), but the fact is that many members of the rival red-shirt United Front for Democracy against Dictatorship (UDD) have now joined the UTN, he said. The party is likely to gain support in the South, where Gen Prayut is popular, observers said.
Pheu Thai, meanwhile, urged the Election Commission (EC) to monitor Gen Prayut's role as prime minister to ensure he cannot abuse his power and use it as an opportunity to woo votes and exploit state organisations to support the UTN's campaign.