Front-runner
Etymology
From racing, both horse and foot, where the front-runner sets the pace at the head of the field; in some uses it also named a horse that runs best only when in front. It moved into politics and business for the current favorite. Leading brings its own pressures, since rivals aim at whoever is ahead.
noun · /FRUNT-run-er/
The competitor currently in the lead and most expected to win.
What it names
The leader’s double-edged position — ahead, but also the one everyone is chasing and scrutinizing.
Example
As the front-runner, she drew every attack in the debate.
Related idea
The front-runner is the visible leader, whereas a dark horse runs unnoticed until it suddenly closes the gap.