The 25-year-old completed a medical at Sixfields on Thursday. He scored nine goals in 22 games at Darlington last season.
Sampson told BBC Radio Northampton: "If he scores the ratio of goals Adebayo Akinfenwa did, he'll be a favourite.
"He's not guaranteed to start, every shirt is up for grabs and we'll look at it during pre-season."
Akinfenwa hit 17 goals in League Two last season, before being released this summer after failing to agree a new contract.
Meanwhile, Sampson says that midfielder Abdul Osman, who is on a weekly contract at Sixfields, will have the same chances to play first-team football as anyone else in the squad.
"I want him to stay and he says he wants to stay, but not on the terms we've offered him," Sampson added.
"We won't be changing those terms. It's not ideal, but he's training well, so I've no qualms about playing him in the team."
Former captain Andy Holt looks set to continue at centre-back this season, where he played at the end of the 2009/10 campaign.
Sampson said: "He can play at left-back or left wing, or even up front, but I see him as a centre back.
"He's got a good football brain and as he's only 32, he could be a good centre-back for a few years."
Source: BBC Sport
Source: BBC Sport