Levein was sacked on Thursday with the club second bottom of the table after one win in 18 league games stretching back to last term.

Stewart believes Hearts owner Ann Budge had to act amid "damning" stats.

"It's a club that are well placed to progress quickly now," Stewart said.

"Any manager looking at that job will be thinking, please let me in there. All the tools are there.

"Ultimately, it's one man who has been holding it back and he has now been relieved of his duties. Massive underachievement, huge failure in the time he's been in charge.

"Ann Budge has done so much good work off the field, but this was really beginning to tarnish her reputation among the supporters.

"It's a huge call, but a very positive one."

Stewart, a vocal critic of Levein - who has also been removed as director of football but will see out the final months of his contract in a backroom role - suggested Jack Ross will be at the forefront of Budge's thinking for a replacement.

"He's been at the club before and was earmarked as the guy who would then become head coach," Stewart said.

"Very much in the same vein as the Scotland job, Stevie Clarke was the obvious option. But you need to have a look at who else is out there."

Levein began his second spell as manager in August 2017 and led Hearts to successive sixth-place finishes.

But the downturn has been drastic since the club topped the table after 10 games last season, taking just 34 points from 39 matches and failing to win at home in the league since March this year.

"He's been given such an unprecedented length of time for someone who has done so poorly," Stewart added. "But the reality has hit home that there was no corner about to be turned.

"This has been a long straight that's been a downward trajectory all the way."

'His signings haven't worked' - analysis

BBC Scotland's Edinburgh sports reporter Brian McLauchlin

At no point since February has Craig been able to put out his strongest team due to injuries. However, he has had a big budget to spend and the majority of the signings have not worked.

The morale at the club is as low as it's been in the last five or six years.

I'd be very surprised if [interim boss] Austin MacPhee is appointed long-term manager of the club. I'm not convinced he is the most popular figure around Tynecastle, within the dressing room or within the club as a whole.

'Cup final papered over the cracks'

Former Hearts defender Allan Preston

This is not a witch-hunt against Craig Levein. Far from it. Results weren't good enough, performances weren't good enough, and it was time to go.

He should have bowed out gracefully after last season's Scottish Cup final and gone back to director of football.

That was the easiest run to a final in Hearts' history and was papering over the cracks, because this season has been absolutely dreadful.