JetBlue’s $3.8 billion bid to buy Spirit Airlines has been endorsed by two firms that advise major investors on how to vote.

Institutional Shareholder Services and Glass, Lewis & Co. recommended that Spirit stockholders vote to accept JetBlue’s offer when they vote on Oct. 19.

Spirit CEO Ted Christie said today that the companies are continuing to make progress toward completing the transaction.

The last major hurdle to JetBlue buying Spirit is the Justice Department, which is reviewing the deal for possible antitrust concerns. Government lawyers are currently in court in Boston, asking a federal judge to kill a partnership between JetBlue and American Airlines, which the government says will reduce competition and lead to higher fares.

JetBlue won a bidding war with Frontier Airlines to get Spirit, which is based in Miramar, Florida, and is the nation’s largest budget carrier. New York-based JetBlue Airways says the deal will make it a stronger competitor to American, United, Delta and Southwest.