Strictly is back in the autumn and we'll have a new face on the panel after Len stepped down last year following more than a decade on the BBC series.
Pro dancer Kevin Clifton insisted he doesn't know anything for sure, but says two names have been touted more than others.
"I've only seen some of the rumours of who it could be, like everyone else," he explained. "I've seen rumours of Anton [Du Beke], I think he'd be great. Karen Hardy, she'd be great."
He told the Daily Express: "They're probably the two frontrunners."
Meanwhile, current Strictly judge Darcey Bussell has revealed that she and fellow judges Bruno Tonioli and Craig Revel Horwood have been left in the dark by show bosses on who Len's replacement would be.
She told the Sunday People: "We don't have any idea what will happen and I know they're not going to tell us until the last minute.
"It's gone very quiet all of a sudden on the rumoured names front," she continued. "I'm nervous - it's a good nerves, not bad nerves - but, yeah, I'm getting excited."
As well as replacement for Len's place on the panel, his role as head judge is also up for grabs.
Darcey said she didn't know who it would be going to but suggested: “I suppose maybe it would be Craig – but he’s a bit of a producer now. He produces a lot behind the scenes.”
Strictly Come Dancing will air on BBC One in the autumn.