A swing in Chinese votes in the next general election, as seen during last Saturday’s twin polls, could see the effects of 2013's Chinese tsunami recede with negative consequences for the opposition.

In Sungai Besar, a swing of about 10 percent of Chinese voters had cost the opposition around 1,300 ballots.

Based on a Malaysiakini simulation using the 2013 polls results, a similar shift of 10 percent of Chinese ballots to BN could result in the opposition losing 12 parliamentary seats in the peninsula and one Sabah seat.

These seats are Alor Setar, Bukit Gantang, Sungai Siput, Kampar, Raub, Temerloh, Sepang, Lembah Pantai, Teluk Kemang, Bukit Katil, Bakri, and Batu Pahat in the peninsula, and Sandakan in Sabah.

The simulation also shows that the opposition would lose three seats in Sarawak, namely Sarikei, Sibu and Miri. However, this does not take into account the shift in voters' constituencies caused by the Sarawak redelineation exercise.

It should be noted that, to some extent, Chinese voters do swing back to BN during by-elections when there is no possibility of changing the government, as observed in the 2014 Teluk Intan by-election.

And as observed by Saturday's turnout, outstation voters are less likely to make the journey home to vote during by-elections, thus increasing the likelihood of a significant swing.

But based on the simulation, even a smaller shift of 5 percent can dent the opposition, taking away six seats, namely Bukit Gantang, Temerloh, Sepang, Teluk Kemang, Batu Pahat, and Sandakan.

Sarikei, Sibu and Miri would also fall to BN, based on the pre-redelineation 2013 data.

Seats previously contested by PAS may also be in danger of falling to BN if both PAS and Amanah are contesting, possibly splitting the Malay votes and giving the ruling coalition an advantage.

Under the current first-past-the-post system, the candidate with the most votes wins, even if the cumulative number of votes for other nominees surpass those of the winner.