Eight years ago, Texans were bombarded with television ads urging them to back Barack Obama or Hillary Clinton, both of whom were still slugging it out for the Democratic presidential nomination.

This year, a similar barrage of presidential primary campaign ads appears unlikely, as the biggest spender — a super PAC backing former Florida Gov. Jeb Bush — canceled its entire media campaign. With a week to go before the March 1 primary, no other campaign or group is expected to fill the advertising vacuum.

Right to Rise USA, the super PAC supporting Bush, had booked $4.4 million worth of February airtime in Texas, according to SMG Delta, which tracks ad spending. After Bush suspended his presidential campaign Saturday following his fourth-place finish in the South Carolina primary, Right to Rise USA quickly pulled the last of its ads. The group had previously announced a series of delays in its Texas campaign as Bush struggled to gain traction in states earlier in the primary calendar.

Right to Rise USA spokesman Paul Lindsay confirmed Monday that the PAC has asked stations to cancel “any and all future advertising” planned, including ad buys on major networks in the state's largest markets including Houston, San Antonio, Dallas and Austin.

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Although no campaign has planned an ad buy even close to the scale of Right to Rise, Conservative Solutions PAC, which is backing U.S. Sen. Marco Rubio of Florida, recently began making ventures into Texas markets as part of a broader media sweep into Super Tuesday states. 

In the three days since Rubio’s second-place finish in South Carolina, the pro-Rubio PAC has purchased some airtime in Texas, including more than $50,000 in the Austin market and $160,000 in the Dallas market, according to filings by broadcast stations with the Federal Communications Commission. The largest broadcast stations in four major markets — Dallas, Austin, San Antonio and Houston — had not reported any ad buys from other presidential campaigns as of Monday. 

Polls suggest U.S. Sen. Ted Cruz of Texas and billionaire Donald Trump leading in the race for Texas Republican voters. Neither campaign has purchased airtime on Texas broadcast stations in the state's largest markets, according to FCC records.

Similar to their Republican counterparts, Democratic presidential frontrunner Hillary Clinton and U.S. Sen. Bernie Sanders of Vermont are also largely absent from the broadcast airwaves in the largest Texas media markets. Clinton's campaign is currently running broadcast ads in Waco, Beaumont, El Paso and the Rio Grande Valley. Sanders has been running ads in Wichita Falls since last week.

Clinton has also purchased approximately $40,000 in airtime targeting Waco and Harlingen on Time Warner Cable, which has not reported ad buys from any other presidential candidates. (Cable networks are not currently required to post political ad sales online, but Time Warner Cable chooses to do so.)

Even if Right to Rise USA had maintained its ad campaign, ad spending by presidential campaigns in Texas still likely would have been a fraction of what the state saw in 2008. That year, the Obama and Clinton campaigns spent a combined total of about $15 million in advance of the Texas Democratic primary, according to an analysis by the Wisconsin Advertising Project.  

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Nick Stapleton, research director at SMG Delta, said he doesn’t expect any candidate will launch an ad campaign similar in scope to Right to Rise USA’s planned media blitz before Super Tuesday. He noted Texas has 20 separate media markets, the highest number of any state.

“They were really the only super PAC with that kind of capacity,” he told the Tribune Monday. “They were way ahead of the pack — they had seven states booked before the March primaries, where everyone else was focused primary by primary.”

The shifting nature of the race means candidates have to make tough decisions about where to advertise, Stapleton added.

“Up until now, it’s always been a single-state race — people focused on their game in Iowa. Some were just focused on New Hampshire. They got to South Carolina quickly. But now it’s becoming a national race,” he said. “You have to start making those strategic decisions about which voters you want to hit.”

Texas is one of 11 states voting on March 1, and by mid-March, about a dozen more states will have followed.

Erik Potholm, a Republican consultant who monitors media buys, said two other Republicans still in the race — Rubio and Ohio Gov. John Kasich — are best positioned to gain from Bush's withdrawal, but neither campaign is likely to invest much money on buying airtime to reach those voters in Texas.

“The Rubio and Kasich campaigns are happy that Bush is out, but TV stations certainly aren’t,” Potholm said.

Abby Livingston contributed to this report.