The new Business and Professionals Alliance political grouping has warned the government it should not take its support for granted.
The comment came despite its vice-chairman, Jeffrey Lam Kin-fung, being appointed to the Executive Council with New People's Party chairwoman Regina Ip Lau Suk-yee this month.
Lam said his appointment would not make his party a "voting machine" in Legco. "The government needs firm support from the pro-establishment parties, but its policies must benefit Hong Kong in the long run," he said. "Our seven votes are not guaranteed to go to the government if its policies turn out otherwise.
"I am not going to be a political vase in Exco, nor will our party become a voting machine that supports the government in every case."
Lam was a core supporter of Henry Tang Ying-yen's doomed campaign for chief executive, and his political grouping, formerly known as Economic Synergy, was a loyal ally of the previous government.
The group recently rebranded itself to form the Business and Professionals Alliance, consisting of seven lawmakers.
His appointment by Chief Executive Leung Chun-ying to the top policymaking body is seen as a sign of reconciliation between the Leung and Tang camps, and a consolation prize for the business sector after Tang's defeat.
Lam said the city had become increasingly polarised and a populist trend was apparent.
"We can see confrontational mindsets between the public and the government, labour and business sectors, pro-establishment figures and pan-democrats," he said. "Public discussion has become irrational, with the business sector demonised."
Policies such as the minimum wage and competition laws, and moves to legislate for paternity leave and standard working hours, were worrying investors.
"I hope to be a channel to reflect the concerns of the business sector in the policymaking process, and try to strike a balance between different interests," Lam said.
Speaking of the difficulties faced by Leung's administration, Lam said the ministers had to become competent salesmen to promote their policies.
"If the government believes the policy is going to benefit Hong Kong in the long term, they should convince the public and not back down easily," he said, referring to controversy about a proposed HK$2,200-a-month old-age living allowance.
Lam said Exco members, including himself, should also act as salesmen. "When the chief executive invited me, he said Exco members might also need to reach out to the community. I am perfectly willing to join in."