One of the big downtown Dallas law firms that was wooed by new development in Uptown has had a change of heart.

Longtime downtown attorney firm Vinson & Elkins has decided to stay in the Trammell Crow Center skyscraper.

More than a year ago, Vinson & Elkins announced that it would leave the Ross Avenue skyscraper when its lease was up in 2018.

Vinson & Elkins signed a deal to lease about 80,000 square feet in The Union office development being built at Cedar Springs Road and Akard Street in Uptown.

But now the law firm - which has about 145 Dallas attorneys and support staff - has shifted gears and renewed its lease in the Trammell Crow Center, downtown leasing agents say.

It's one of the few times real estate brokers say they have seen such a move.

The completion date of The Union project no longer met Vinson & Elkins schedule, according to brokers.

"While timing did not align with the specific needs of Vinson & Elkins, The Union remains on track for a 2018 delivery and we look forward to announcing new tenants soon," a spokesperson for the project said in an email.

Vinson & Elkins' lease renewal comes after Trammell Crow Center recently announced a $135 million renovation that includes construction of new retail and restaurant space, parking and a hotel that will join the 32-year-old office tower.

Law firm Baker & Botts and financial services giant Goldman Sachs have recently committed to large blocks of office space in the landmark high-rise.

Keeping Vinson & Elkins is an unexpected coup for Trammell Crow Center, according to downtown leasing agents who've been tracking the deal.

Vinson & Elkins was just one of a handful of downtown law firms that were lured by newer buildings in Uptown.

Akin Gump just announced that it has rented a large block of offices in Union project. And the development has also signed leases with accounting firm Weaver.

Gardere Wynne Sewell LLP and Sidley Austin LLP have taken space in Uptown's new McKinney & Olive tower.

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