Barring unexpected developments, the chief executive will also lead Mr Leong by a big margin in popularity standings in opinion polls.

That having been said, Mr Tsang is clearly confronting a new, and more difficult, ball game.

Never mind that Mr Leong's leadership calibre and qualities remain a big unknown: his expected success in securing the minimum 100 nominations from the Election Committee has already posed no small challenge to Mr Tsang.

The chief executive must soon find answers to some key questions relating to his re-election bid: when, how and, more importantly, why.

With Mr Leong's election campaign already up and running for almost two months, the pressure - real or imagined - will grow on Mr Tsang to announce his intention to run for re-election.

Speaking at a closed-door lunch with community leaders last month, Mr Tsang reportedly gave three reasons for not making an early entry into the ring.

First, he said the Election Affairs Commission had not yet publicised detailed electoral arrangements, including the nomination period.

Second, he needed more time for preparation. Finally, he said he wanted to minimise the impact of the campaign on his performance of his duties as chief executive.

Those are legitimate reasons. But he has put himself at an early disadvantage by choosing not to fight back against Mr Leong's alternative initiatives on air pollution and education, under the election theme of 'The Hong Kong we want.'

The other approach, nevertheless, would not be risk-free. It would raise the political temperature if Mr Tsang engaged Mr Leong in public election debates even before the nomination period began. By doing so, he would in effect widen the 'small circle' election to the broader arena of society at large.

It would further complicate Mr Tsang's election strategy to shift his target from the 800 Election Committee members - who will do the voting - to the 7 million Hongkongers whose views Mr Tsang cannot afford to ignore.

One difficult question is whether he should, as he did in last year's election, go after every nomination from the 800 Election Committee members in order to secure an overwhelming backing.

Or should be merely meet the 100-nomination threshold and, instead, focus his campaign on winning over the people?

If he adopted the latter approach, how would he reconcile the potential clash of interests that might arise between the sector-based Election Committee and the general society of our city?

These questions boil down to the key question of why Mr Tsang wants a second term - assuming he does.

Is it because he simply wants more time to turn his promises, outlined in the past 18 months, into reality?

Or is it because he aspires to start afresh in a second, and last, term with no political baggage, more visionary goals and initiatives, and a more assured ruling team after a period of caretaker government?

Two years ago, Mr Tsang caught wind of the change that his career was about to take - succeeding Tung Chee-hwa before the latter's term expired. As Mr Tung quit, Mr Tsang was seen as the natural successor.

Now that those expectations have grown into reality and circumstances have changed, Mr Tsang faces the real test: convincing doubters why he should be given five more years.