TAMPA — The Republican National Convention is expected to have an economic impact in the Tampa Bay area of at least $153.6 million.That's the estimate released Friday from a Tampa-based research team at Jones Lang LaSalle, a publicly traded financial and professional services firm specializing in real estate.The firm said that's a conservative estimate, and the impact could exceed $173 million."Any way you look at it, the convention is going to be a shot in the arm for Tampa Bay's economy and tourism base," Jones Lang LaSalle research analyst Stephen Siena said.The estimate is based on adding together the direct spending by the Tampa Bay Host Committee, which is working to raise and spend $55 million in support of the RNC, and visitors who will collectively spend more than $85.6 million.That yields an estimate of direct spending of $140.6 million. That estimate also includes security spending by the city of Tampa, which received a $50 million federal grant, not all of which will be spent locally, Siena said.The firm reached its final estimate by applying a multiplier to track the impact of money as it is respent in the local economy and subtracting normal spending crowded out by the convention — such as downtown workers who stay away to avoid the traffic or nonconvention visitors who skip a trip to Tampa they would have otherwise taken.Overall, the estimate from Jones Lang LaSalle is generally in the ballpark with — though on the low side of — the estimate offered by the Tampa Bay Host Committee.Host Committee president Ken Jones regularly says he expects $175 million or more in direct convention spending. That will come from four sources:• The host committee.• The city's security grant.• The $18 million that the convention itself gets from the Federal Election Commission.• $40 million to $50 million in visitor spending on hotels, meals, transportation, gifts and other purchases.Even if not all of the spending is local, Jones said he's confident that the local impact will exceed $170 million once a multiplier is factored in."Our numbers were based on a logical calculus and a very thoughtful deliberation about the amount of money that we believe will be spent in connection with this event," he said. "We didn't throw a dart at a board."Convention's theme looks aheadThe convention announced Friday the theme for the four-day event: "A Better Future.""Americans are ready for a new direction, and that's why our convention will focus on the Romney-Ryan vision for a better future," Republican National Chairman Reince Priebus said in announcing the theme."Our message is pretty straightforward, which is this is a critical time for the country, a time when we decide what kind of America we're going to have," former Massachusetts Gov. Mitt Romney said in a conference call this week with convention staffers in Tampa. "The president is making us more and more like Europe, with a nation dominated by government. Our intent is instead to restore the principles that made us the nation we are."RNC, Host Committee unveil mobile appThe RNC and the Tampa Bay Host Committee on Friday unveiled a mobile application to help delegates and others navigate the convention and the Tampa Bay area.With the mobile app, users can watch live convention coverage, use social media, look at maps, play trivia games, go on a scavenger hunt at local businesses, check the convention's master calendar, and get local news, fun facts about Florida, and transportation, shuttle, taxi service and weather information.In addition, the convention's schedule will be released through the app. On Monday, the schedule for Aug. 27 will be released, with similar one-week-in-advance RNC schedules coming out in the following days.The app, "Tampa 2012," was developed by AT&T, the convention's official wireless provider.It is available for iOS (iPhone and iPad) and Android devices, and through a mobile website for BlackBerry and other smartphone users. Instructions and links to the mobile app are at connect.gopconvention2012.com.Connie Mack to address RNCNominated by Florida Republicans to run for the Senate, U.S. Rep. Connie Mack IV is among the latest batch of speakers this week named to address the convention. The others are:• U.S. Sen. Rob Portman of Ohio, once seen as a strong contender to be Romney's running mate.• Louisiana Gov. Bobby Jindal.• Virginia Gov. Bob McDonnell, who chairs the RNC's platform committee.• U.S. Sen. Kelly Ayotte of New Hampshire.• Artur Davis, a former Alabama congressman and Barack Obama supporter who recently announced he is joining the GOP and supporting Romney.