KUALA LUMPUR - The so-called "crooked bridge" never took off in the 14 years after it was first mooted by then prime minister Mahathir Mohamad, but the recurring national issue may yet take down a second successive Malaysian leader.
In 2003, just before ending his 22-year tenure as PM, Tun Dr Mahathir announced that Malaysia would go ahead and build a crooked bridge - a six-lane S-shaped highway that would curve in such a way that it allows vessels to pass under it - if Singapore refused to demolish its half of the Causeway.
The failure of his successor Abdullah Badawi to push ahead with replacing the Causeway led Dr Mahathir to viciously attack him in 2006. The move, observers say, eventually pushed Tun Abdullah to resign in 2009.
The still influential Dr Mahathir now claims that Datuk Seri Najib Razak also failed to keep his promise to build the crooked bridge, and has asked the prime minister to step down amid a host of other outstanding issues plaguing his administration.
Here's a look at the "crooked bridge" issue:
Why does Dr Mahathir want the bridge?
He first mooted replacing the link from Johor Baru to Singapore with a bridge in 2001 to ease traffic congestion, allow stagnant water to flow and improve the marine environment as well as allow ships to sail across the Johor Strait - which would be a major boost for Johor's two ports.
Why did Mr Abdullah not proceed?
Singapore has never agreed to the complete demolition of the Causeway without other bilateral issues also being sorted out as a package. Mr Abdullah had first tried to go ahead with a full bridge while allowing Singapore's military to use Johor airspace. But due to a pushback against the idea, he returned in 2006 to the idea of a "scenic bridge" as he called it, to be built only in Malaysian territory. He made an amazing turnaround less than three months later, announcing that the entire bridge project would be abandoned despite RM100 million (S$37 million) already committed, citing public concerns over the sale of sand to and use of airspace by Singapore.
Why did Mr Najib not proceed?
Mr Najib and his Singaporean counterpart Mr Lee Hsien Loong had agreed instead to building a third link between Johor and Singapore. According to Dr Mahathir, Mr Najib told him that Malaysia could not proceed with the crooked bridge as there was an agreement not to touch the Causeway unless both sides agreed.
"But he couldn't show me the agreement," Dr Mahathir said.
What was Singapore's position?
Singapore saw "no significant benefits", especially when their half of the deal would incur "huge financial costs". However, it said it was amenable to discussing the project as part of a package including other bilateral issues, which could include the use of Malaysian airspace by the Republic of Singapore Air Force, the purchase of sand and raw water from Malaysia.
Malaysia halted discussions in April 2006 following protests from Umno Johor over Singapore's requested trade-offs.