The four-time Champ Car title-winner has been linked with Coyne since late August, when his former engineer at Newman/Haas Racing, Craig Hampson, departed Andretti Autosport for Coyne’s Plainfield, Ill.-based squad.

Bourdais has raced for Coyne in the past – a partial season in 2011 – before joining Dragon Racing’s now defunct IndyCar team, for whom he scored three podium finishes in 2013.

Bourdais’ past three seasons at KVSH Racing have yielded four wins and two tenth places in the championship. But this year inconsistent results saw him slip to 14th in the standings, and with KV’s future direction looking uncertain, Bourdais elected to jump ship.

Coyne told Motorsport.com: “We’re going to Gateway with a ‘TBA’! But your guess is pretty good. The deal isn’t completely done yet, but we should be able to announce Sebastien in the next couple of days. And yes, Craig [Hampson] will be at the test.

“It’s going to be nice; they’re a strong combination, as we saw year after year back in Champ Car.

“But like I said, it’s not finalized yet, I guarantee you that.”

Coyne, who for many years struggled to confirm his drivers before the last few weeks of preseason testing, last December was able to reveal both Conor Daly and the late Bryan Clauson as full-time and Indy 500-only drivers respectively. He joked that this year he planned to beat his personal ‘record,’ telling Motorsport.com: “The Sebastien deal should happen in the next couple of days, and the second car may also be announced by the end of this month. Wouldn’t that be something?!”

Asked if his promising part-time hire from this year, RC Enerson, was a strong candidate for the second seat, he said: “Yes. There’s a long list, but RC is on it for sure. I want it to be one person in that second car for the whole season, that’s the aim… But I say that every year, don’t I? We did manage it a couple of seasons [2012 with Justin Wilson and James Jakes, and 2014 with Wilson and Carlos Huertas].

“It doesn’t get any easier for a team or a driver to find sponsorships big enough to last a whole season,” Coyne continued. “IndyCar isn’t wrong: we are going the right way with TV figures and coverage and so on, but it’s coming from a low level. People say NASCAR ratings are falling, but they’re coming down from such a high level.”