Jennings averaged just over 18 in their recent 4-1 series victory over India and has not scored a Test century since his debut knock in Mumbai in 2016.
"I'm sure he will be a bit nervous about which way it will go. He scored runs in India on spinning wickets and I'm sure that will be in his favour," said Bayliss.
"But he is a big boy, he knows runs on the board count as well. All of those points will have to be discussed and I can't say at this stage or another whether he will go or not."
If Jennings is not retained, England will once again have to look back to James Vince. "If you take Joe out of the equation, Vince has probably been our best No. 3 over the last few years," said Bayliss. "I gave him the challenge when we dropped him to go back and score plenty of runs. Averaging 40 in county cricket is not good enough. You have got to average 50 or 60 and, take out this last game, he was close to that and made some big hundreds so he has done what we asked of him. Whether he makes the cut or not we will find out in a week."
England, who will be without Alastair Cook after the 33-year-old retired as their most prolific scorer in tests, are expected to name their squad next week.
Bayliss confirmed that Joe Denly and Rory Burns are also vying for a spot in the squad.
"I have not seen Denly in the last couple of years," he said. "He has made some runs this year and apparently he is a decent player of spin. He can play the short ball but so can a few others. Vince for example. And obviously Burns is making a lot of runs at The Oval. "I am sure all three guys will get a hearing and there might be more than one spot in the touring party."
England will play five One-Day Internationals and a Twenty20 International in Sri Lanka before the three-Test series gets underway on November 6 at Galle.
alastair cookEnglandJames VinceJoe DenlyKeaton JenningsRory Burnssri lanka vs england 2018Trevor Bayliss
First Published: September 13, 2018, 12:57 PM IST