McLaren has finally found its way back into the IndyCar paddock. Ending months of rampant rumors and speculation, McLaren and Arrow Schmidt Peterson Motorsports announced Friday morning that following the conclusion of the 2019 NTT IndyCar season, they will team up to form Arrow McLaren Racing SP.

The program will bring two cars and Chevrolet power to the NTT IndyCar Series paddock in 2020.

The deal, made official Friday but in the works for months, has already begun to send shockwaves throughout the IndyCar paddock with perhaps the biggest being a result of the new engine partnership with Chevrolet.

Arrow SPM’s infrastructure will remain intact, while McLaren, which last competed full time in IndyCar in 1979, will bring its “technical expertise, commercial experience and marketing strength” to the program. Arrow SPM co-founders Sam Schmidt and Ric Peterson will continue in their current roles, while McLaren Racing Sporting Director Gil de Ferran will lead McLaren’s IndyCar involvement with a group independent of the Formula 1 team.

"I’m extremely proud of the team that Ric and I have built and that a legendary brand like McLaren Racing has decided to partner with us to form Arrow McLaren Racing SP to continue our march to the top of IndyCar," Sam Schmidt said in a news release.

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“IndyCar has been part of McLaren since our early years of racing,” added McLaren CEO Zak Brown. “And the series today provides not only a commercial platform to continue to grow our brand in North America, but competition with some of the best teams in international motorsport.

“I’m absolutely delighted that we will expand our relationship with Arrow Electronics across both F1 and IndyCar, while renewing our long affinity with Chevrolet as our engine partner.”

Arrow SPM had one year remaining on its current engine deal with Honda and, according to multiple IndyCar sources, were told in no uncertain terms by Honda executives that partnering with McLaren was forbidden.

Honda still hasn't forgiven McLaren for the way it severed its ties with the manufacturer a few years ago in Formula One. Because of that, the mandate from headquarters in Japan has been that it will not do business with McLaren in any racing series. That is ultimately what prevented Andretti Autosport from forging a partnership with McLaren, as it had been trying to do for more than a year, according to IndyCar sources.

Andretti worked to try to mend those fences but came up short. So did Arrow SPM. However, Schmidt and Peterson opted to go against Honda’s wishes and move forward with the deal anyway, putting Honda in the position of having to decide whether it would work with McLaren again or let Arrow SPM out of the year remaining on its contract.

While the details of such an arrangement have not been revealed, it appears Honda has let -- or intends to let -- Arrow McLaren Racing SP out if its current contract, freeing it to sign with Chevrolet.

While Honda has no intention of airing its grievances publicly, multiple IndyCar sources have confirmed that Honda leadership is not pleased with the way Friday’s deal came to pass.

"HPD is proud of its numerous accomplishments in partnership with Arrow Schmidt Peterson Motorsports, which include all seven of the team’s NTT IndyCar Series victories to date, as well as two coveted pole positions for the Indianapolis 500," the manufacturer said in a statement. "Although we regret that this partnership will be coming to an end in advance of the 2020 season, HPD has the utmost confidence in the strength and commitment of its remaining partner teams, all of whom have won at least one NTT IndyCar Series race in each of the past two seasons. We look forward to demonstrating that same type of depth across our entire lineup for many years to come.”

Making the situation even more awkward, Arrow SPM and Honda will remain partners for the rest of the 2019 season.

The team has not made any announcements about who will drive Arrow McLaren Racing SP’s cars in 2020.

Six-time race winner James Hinchcliffe is under contract through 2020 and tweeted Friday that he expects to be with the team. The new arrangement, however, will have an impact on his personal sponsorship with Honda Canada and his role as an international Honda spokesman.

"It is rather unfortunate what this means for our relationship with Honda," Hinchcliffe said in his tweet. "They are another company that has done so much for me and when the time is right a discussion to what that means for my partnership with them and HondaCanada will need to occur but that is secondary right now to this exciting news."

Meanwhile, Marcus Ericsson’s contract expires at the end of the season, and it does not appear likely the Formula One import will be retained by Arrow McLaren Racing SP.

The team has already been in discussions with multiple drivers to sign on in 2020, including Alexander Rossi and Colton Herta. Rossi re-signed with Andretti Autosport, however, and it appears Herta is closing in on joining him. Multiple teams jockeying for Herta, including Arrow McLaren Racing SP, have halted their pursuit, and three IndyCar sources said they expect Herta to pilot a fifth Andretti Autosport car in 2020.

Andretti Autosport COO Rob Edwards would not confirm that a deal had been reached with Herta. He did, however, reiterate that after the re-signing of Rossi, keeping Herta in the family immediately became the team’s top priority.

“We’re continuing to work to make it happen, but nothing is done with him,” Edwards said of Herta, whose father, Bryan Herta, co-owns the No. 98 car with Andretti. “A fifth car has always been in the realm of possibility if it was for Colton.”

With Herta seemingly off the table, Arrow McLaren Racing SP has set its sights on a different target, but one quite familiar to Herta and IndyCar fans alike: Patricio O’Ward.

According to multiple sources in the IndyCar paddock, the team is in discussions with Herta’s former Andretti Indy Lights teammate and 2019 Carlin Racing driver.

O’Ward, the 20-year-old member of Red Bull Junior program, is currently driving for the Mugen Super Formula Team in Japan. Along with ties to Andretti and Carlin, the young Mexican standout also has ties to both McLaren and Arrow SPM. Brown spoke with O’Ward at Long Beach about the possibility of joining McLaren in the future, while Schmidt expressed interest in him shortly after he was released from his contract with Harding Steinbrenner Racing in February. Schmidt told IndyStar then that he “would love” to find a spot for O’Ward but couldn’t at the time.

Other drivers remain a possibility for Arrow McLaren Racing SP, including former Sauber Formula 1 driver Felipe Nasr, who recently tested with Arrow SPM.

Another piece of the puzzle left to figure out is Meyer Shank Racing, which previously shared a technical alliance with Arrow SPM. Because of Meyer Shank Racing's shared ties to Honda and AutoNation and their previous relationship during the 2017 Indianapolis 500, a pact with Andretti Autosport appears to make the most sense. However, at least one other team -- Rahal Letterman Lanigan Racing -- is known to be in the mix as well, according to an IndyCar source. Team principals Bobby Rahal and Michael Shank share Ohio roots.

"We are getting closer to finalizing our plans and expect to be making agreements for a multi-year program in IndyCar," Shank told IndyStar. "Our discussions with AutoNation and SiriusXM continue to to be very positive. I feel really good about how things are coming together, but we've just got to get everything final before making any announcement ... (about) our schedule, technical program and partners for 2020 and beyond."

One thing is clear when examining all these moving parts: The ripple effects of the McLaren-Arrow SPM partnership could be massive.

More immediately, however, McLaren’s move to IndyCar can be viewed as a positive step for the series. McLaren is one of the most prestigious racing programs in the world, and bringing it into the fold should be considered a win, IndyCar President Jay Frye said.

“IndyCar is proud to have an iconic organization as McLaren joining the NTT IndyCar Series full time in 2020 with Arrow Schmidt Peterson Motorsports,” Frye said. “McLaren owns such a rich history in motorsports, the automotive industry and technology, and will be a viable competitor in our series for years to come.”

For the series, the move also helps restore some balance between the two engine manufacturers. Two more cars brings Chevrolet's count to 10, while Honda drops from 13 full-timers to 11.

Follow IndyStar Sports reporter Jim Ayello on Twitter, Facebook and Instagram: @jimayello.