The exit of four Sarawak parties from the Barisan Nasional (BN) pact on Tuesday not only sounds the possible death knell for Malaysia's longest-ruling coalition, but also heralds a new system of political deal-making in the country.

BN, which had governed Malaysia for six decades, was ousted from power in last month's general election. Tuesday's decision means the once-invincible 13-party pact loses another 19 MPs, and is now reduced to a four-member team of dominant party Umno plus three allies, which, between them, count 57 lawmakers in the 222-seat Parliament.

Prime Minister Mahathir Mohamad, who helms the Pakatan Harapan (PH) government with a simple majority of 125 seats, now enjoys the comfort of having no major opposition force to contend with.

The four Sarawak parties - known as Gabungan Parti Sarawak - have said they will not join PH, but would "cooperate and collaborate" with the federal government on issues of national and state interest.

The remaining 18 seats in Parliament belong to opposition party Parti Islam SeMalaysia (PAS), which controls Kelantan and Terengganu.

The upshot is that decades of one-on-one battles between a grand ruling coalition and its opposition are now replaced by power plays between regional centres of power. Sarawak and Sabah - which are pushing for more autonomy from the federal government as founding partners of Malaysia - are represented largely by local parties. Another power base lies in the country's Malay Muslim majority, many of whom voted for Umno and PAS.

If PH proves an adept deal-maker, it can gain the two-thirds majority support needed to push its reforms through Parliament. In return, the under-developed states of Sarawak, Sabah, Kelantan and Terengganu could receive much-needed grants and concessions from the central government.