President Obama is greeted by Patrick Murphy and Fort Pierce Mayor Linda Hudson upon his arrival at St. Lucie International Airport in March 2015. (Pablo Martinez Monsivais/AP)

A little more than a month ago, Rep. Patrick Murphy was exceedingly well-positioned in the closely watched Florida Senate race: The Republicans running to replace the thought-to-be-retiring Marco Rubio faced a messy primary, while Murphy had consolidated his party establishment’s support against fellow Democratic congressman Alan Grayson.

Since then, the race has been transformed.

Rubio has decided to seek reelection after all, a series of media reports have raised pointed questions about Murphy, and, in recent weeks, outside groups have financed more than $4 million in negative ads targeting him.

The ferocity of the attacks have raised questions among some Democrats about whether Republicans are making an overt effort to take out Murphy in the Aug. 30 primary — thus sidelining a well-financed, centrist candidate in favor of Grayson, a liberal firebrand thought to have less appeal to general election voters.

“I don’t think there’s any secret that Republicans want to run against Alan Grayson,” said Florida Democratic strategist Steve Schale. “He’s sort of our version of Donald Trump.”

The most recent public polling in the race, done in late June by two Florida TV stations, showed Murphy and Rubio neck and neck among likely general election voters.

Suspicions about a GOP effort to boost Grayson over Murphy have been aroused, in part, by media tracking data, which show at least one GOP-affiliated group appearing to target Democratic primary voters rather than a broader swath of the Florida electorate.

The American Future Fund, a 501(c)(4) nonprofit group with ties to GOP super donors Charles and David Koch, has spent $1.5 million on a 30-second cable TV ad highlighting Murphy’s vote in support of the Export-Import Bank. The ads, according to tracking data obtained by The Washington Post, target networks that attract a disproportionate share of Democratic viewers, including MSNBC, while eschewing GOP-heavy networks, such as Fox News Channel.

Also arousing suspicions are the markets in which the ad is airing — Democratic strongholds like West Palm Beach and Gainesville are seeing the ad, while GOP-heavy areas like Fort Myers and Pensacola are not. The American Future Fund did not respond to emails seeking comment.

To several Florida Democrats, the whole thing carries shades of the ultimately successful 2012 effort by Sen. Claire McCaskill (D-Mo.) to promote Rep. Todd Akin in the GOP primary — the candidate McCaskill believed, with good reason, was the most beatable in the Republican field. McCaskill’s campaign produced a sly ad that played up Akin’s conservative bona fides to GOP primary voters.

“I know they feel [Murphy] is a bigger threat than Alan Grayson to Marco Rubio,” said Rep. Alcee Hastings (D-Fla.). “I think that some of their thinking is to drive down Patrick’s positives to negative territory and to boost Grayson, because Grayson wouldn’t stand a chance with Marco.”

Last year, there was a hint that false-flag campaigning might be on tap in Florida: Shortly after Murphy entered the race, the Club for Growth briefly aired a 30-second ad on MSNBC and other networks hailing Grayson for his stance against the Ex-Im Bank, spending $250,000 on the effort. Grayson joined the race a month later. But since then, no GOP-affiliated group has openly spent to prop up Grayson.

What there have been in the past month are a combined $2.7 million in attack ads amplifying reporting done last month by Miami’s WFOR-TV that questioned Murphy’s claims about his business experience. Two separate spots from the U.S. Chamber of Commerce and the GOP-aligned Senate Leadership Fund have sought to make the case that Murphy is untrustworthy.

Together, the three groups running anti-Murphy ads are spending roughly double what Murphy’s campaign and the Senate Majority PAC have spent this month on ads highlighting President Obama’s endorsement of Murphy.

Asked about the outside spending, a Murphy campaign spokeswoman stopped short of fingering an Akin-style cross-party operation but said that “Republicans clearly recognize that Patrick is the strongest candidate to win in November and that’s why they’re unleashing false attacks.”

“These outside groups know that Marco Rubio can’t win on the issues that matter to Florida families,” the spokeswoman, Galia Slayen, said.

McCaskill herself weighed in, saying in a statement: “It’s clear to me that national Republicans want Alan Grayson as their opponent because they know he’ll be easier to beat.”

“That’s a strategy I’m familiar with,” she continued, “but I’m confident it won’t work this time, because Floridians know that Patrick Murphy is a champion for his state, who’ll be the most formidable Democrat to take on Marco Rubio.”

Grayson’s campaign declined to comment on the anti-Murphy spending. Republican operatives who are keeping a close eye on the race say they don’t see a concerted effort to prop up Grayson over Murphy in the primary, but rather a smart bid to define Murphy among general-election voters early in the race — and to force the Murphy campaign and its allies to spend down their war chests earlier than they had planned.

More anti-Murphy spending is definitely on the way.

“Our initial investment and ad should be viewed as a teaser trailer to what will be a sustained paid media campaign that will leave Floridians describing Patrick Murphy with one word — fraud,” said Ian Prior, a spokesman for the Senate Leadership Fund, which spent $1.5 million on Florida ads in July.

The national party committees also have each made eight-figure Florida ad reservations in anticipation of a bruising general-election fight in a state where TV saturation costs upward of $3 million a week. The Senate Majority PAC has reserved more than $10 million in general-election ad time. But that money is not expected to flow until after Labor Day, and the surge of anti-Murphy spending from the outside groups has some Democrats suggesting that more needs to be done sooner.

“What I’m asking the DSCC to do is to do just the reverse, and weigh in and keep the young man’s positives as high as they possibly can,” Hastings said Friday, referring to the Democratic Senatorial Campaign Committee.

Sadie Weiner, the committee’s communications director, would not discuss its spending strategies but said the DSCC is “proud to stand with Patrick, to support him in a variety of ways and eventually, to welcome him to the Senate next year when he replaces Marco Rubio who has shown he’s only out for himself.”