The My Left Foot star insists he would never have even considered portraying Abraham Lincoln in the movie if his friend was still attached to the project, after initially turning down the chance to play the assassinated U.S. President.
However, Day-Lewis reveals Neeson encouraged him to take the role and gave him his blessing after the casting was confirmed.
He tells WENN, "Liam is a friend of mine and Liam was committed to a period of time working with Steven. There came a moment for reasons known to both of them that Liam would do other things and Steven would do other things. But during that period of time whilst Liam was committed to the project, of course it wouldn't have occurred to me to consider it.
"He has been in touch with me about it since and has given me incredible encouragement in the most generous possible way. When I was undecided about doing it he gave me encouragement towards that decision. I just feel I should say that. I can say unequivocally that Liam's Lincoln would have been something I'd like to see.
"The timing worked out this way but it could've easily worked out the other way and I think Liam would've been quite wonderful."