Call it the buzz that comes with power. Malaysian Deputy Prime Minister Ahmad Zahid Hamidi was mobbed by people every time he walked the corridors outside the meeting halls of the just-concluded Umno annual assembly.

A student who just graduated from an overseas college wanted to say "thank you" to the government last Friday, a man wanted to present him a painting, and an old woman wanted to ask for financial help to restore her home that was washed away by floods.

Datuk Seri Zahid entertained them all with wide smiles and firm handshakes, while aides rushed in to ensure that each encounter lasted just seconds as he walked to yet another function. "Take her number and get her details," he told his aides, as the woman called after him: "Thank you, Datuk. Congratulations on your new post."

At the five-day assembly that ended on Saturday, Prime Minister Najib Razak, 62, grabbed most of the media headlines as he faced his toughest party gathering to fend off the twin funding scandals that have rocked the party. By his side, Mr Zahid, also 62, received a lot of attention too as it was his first assembly as his deputy prime minister.

Datuk Seri Najib's promotion of Mr Zahid - who is one of Umno's vice-presidents - as his deputy in government in July has made the latter the man to watch. And with Umno deputy president Muhyiddin Yassin, 68, playing rebel leader to press Mr Najib on questions about the mystery US$680 million (S$960 million) and troubled state investor 1Malaysia Development Berhad (1MDB), the party is looking at Mr Zahid as the bridge between the two estranged leaders.

Mr Zahid told an interviewer last week: "I have no problems with Muhyiddin. At the first supreme council meeting after the reshuffle, I was sitting on his right, and he entertained my questions as if nothing had happened to both of us."

At the same time, Mr Najib trusts him fully, unlike the lack of chemistry between the Prime Minister and Mr Muhyiddin.

Datuk Alwi Che Mat, a Kelantan Umno assemblyman, told The Straits Times: "There must be a high level of trust between the No. 1 and No. 2, that is the most important."

Mr Najib, in an interview with The Star newspaper last week, described his relationship with Mr Muhyiddin when the latter was deputy prime minister as being "too formal".

As for Mr Zahid, Mr Najib's former political secretary, the Premier described their ties thus in an interview with The Star newspaper: "One evening, during the Asean Summit, (as) I was watching the rehearsal, he just turned up and said, I'm here to just give you moral support. That kind of relationship is important between two top leaders. There must be trust and a level of comfort with one another."

Mr Zahid is seen by political analysts and many Umno members as the most popular party leader today, with his no-nonsense approach as Home Minister and easy smiles gaining him fans.

This is not to say that he is popular with the opposition and rights activists, as he had pushed for controversial security laws such as the recently passed National Security Council Bill, and the police under him often threaten to crack down hard on street protests such as Bersih 4.

The climb to the top has been filled with ups and downs for the politician from Perak, whose first job was as an officer at OCBC Bank in Kuala Lumpur.

Mr Zahid, whose parents are Islamic teachers, graduated from Universiti Malaya with a degree in literature. He is married to Datin Seri Hamidah Khamis, 60, and they have two daughters and three sons.

When Anwar Ibrahim was sacked as deputy prime minister nearly 17 years ago on Sept 2, 1998, only Mr Zahid and Mr Muhyiddin visited his house to give moral support, as they were both the closest to the former No. 2. Mr Zahid was soon arrested by then Prime Minister Mahathir Mohamad, accused of being a key supporter of the Reformasi street protests.

He got out after a few weeks, but spent the next six years in the political wilderness until 2004, when he was appointed a deputy minister by former prime minister Abdullah Badawi. Thus when Mr Najib ousted Mr Muhyiddin as deputy prime minister and gave the post to Mr Zahid in July, Mr Zahid was taking over from an old friend.

Mr Najib allowed his new deputy to keep the powerful post of Home Minister with the police, intelligence services, immigration and civil defence under his purview.

Mr Zahid was the political secretary to Mr Najib when the latter was youth and sports minister, and later defence minister. In the 2013 Umno internal polls, Mr Zahid gained the most votes among the three vice-presidents. Today, party members see him as the loyal deputy to Mr Najib who can keep the party steady as it tries to overcome the donation and 1MDB scandals.

Umno delegate Shaharum Sharif from Selangor said: "I believe these issues are being settled and Datuk Seri Zahid has been able to do a good job in helping the president. I hope this will continue."