Mayor Rahm Emanuel is inviting architects from around the world to join what’s expected to be a heated competition to design his $8.7 billion O’Hare Airport expansion plan.

During the week of June 18, City Hall plans to issue a “request for qualifications” for LEAD Architectural Design Services for the massive project that Emanuel calls “O’Hare 21.”

The mayor’s plan calls for demolishing Terminal 2 and replacing it with a new “global terminal” shared by United and American Airlines that would accept both domestic and international flights.

The massive, multi-year makeover also calls for dozens of new gates and additional concourses.

O’Hare would become the first so-called “global alliance hub” in the nation; it will allow domestic airlines and the international carriers with which those domestic airlines partner to all be located in the same terminal.

No longer would passengers connecting to international flights endure the delay and inconvenience of having to ride the O’Hare people mover to the international terminal.

In a city known internationally for its outstanding architecture, Emanuel said it only makes sense to challenge architects from around the world to envision the new O’Hare.

“This is an opportunity to write the next chapter in Chicago’s legacy of architectural ingenuity while sharing the iconic architecture and design Chicago is famous for with visitors from across the country and around the world,” the mayor was quoted as saying in a press release.

“When Chicago opened O’Hare 59 years ago, we positioned our…city at the heart of the national aviation system. Today, the city that makes no little plans is securing our position at the forefront of global cities for the 21st Century.”

Aviation Commissioner Ginger Evans characterized the RFQ as a “significant step forward” in a project that will allow Emanuel to seek a third-term with a job-and-contract-generating, fundraising ace in his pocket.

The mayor views the project as so important to Chicago’s future –– and his own — he rushed out to O’Hare to immediately sign new airline use and lease agreements after the City Council approved the project.

Baked into those leases are higher terminals rents and landing fees that will bankroll the $4 billion in general airport revenue and passenger facility charge bonds that aldermen authorized to get the project started.

“We are excited to launch this search for prominent architecture teams who can support our vision for a state-of-the-art Global Terminal, satellite concourses and a bigger and better O’Hare to serve our passengers,” Evans was quoted as saying.

“We welcome proposals by firms in Chicago and from around the world to compete for the chance to chart the course for an unprecedented expansion at one of the world’s busiest airports.”

American Airlines was alone among airlines in objecting to the new lease agreements because of the five additional gates that Emanuel has awarded to hometown United Airlines, American’s arch-rival.

But American ultimately signed on after the city made a hazy promise to speed construction of three common-use gates that favor American because they’re located at the end of an American concourse.

The City Council’s Black and Hispanic Caucuses had threatened to hold up the $4 billion borrowing that will raise the mountain of O’Hare debt to $13 billion to press their demand for a fair share of jobs and contracts generated by the project.

But they were appeased by the promise to create a task force that will meet quarterly and ride herd over O’Hare expansion contracting and hold Emanuel’s feet to the fire.