Lately, as Murphy has become the clear pick of the party establishment, from the White House on down, Grayson has churned out the descriptions "lickspittle pillock" and —- closer to the 21st century —- party "sock puppet" to deride his fellow congressman.
This week, Murphy's campaign seemingly dipped into the playbook of presumptive Republican presidential candidate Donald Trump in attacking the outspoken Grayson.
Where Trump has had success by tossing nicknames such as "Lyin' Ted" and "Little Marco" at rivals, Murphy broke out the moniker "Angry Alan" for Grayson.
Democrats see this year's race for the seat being vacated by Republican Sen. Marco Rubio as a potential opportunity to help grab control of the U.S. Senate from the GOP. But the tone of the Democratic primary has focused heavily on personal attacks, rather than issues.
Political observers said such a tone more and more has become the political normal.
Susan MacManus, a political-science professor at the University of South Florida, called the Murphy-Grayson contest "celebrity politics."
"You wonder about the effect of the presidential election on down-ballot races and this is reality-show politics all the way down the ballot," MacManus said. "This is the tenor of campaigns in 2016, whether the public likes it or not. A larger share of the public doesn't, but they're still going to vote."
MacManus added that the tone is calculated by candidates and campaigns to attract voters, especially in close primary contests where there may be fewer differences on issues.
"It's a different tone, and different is often more engaging," MacManus said.
University of Central Florida political-science professor Aubrey Jewett said he initially was surprised that more attention hasn't been placed on issues, given that there are differences between the Democratic challengers.
Murphy and Grayson have differed in votes over the Keystone XL pipeline, the reauthorization of the U.S. Export-Import Bank, providing aid to Ukraine while condemning Russian President Vladimir Putin and the use of executive orders by President Barack Obama.
"There's always a chance that issues may break out as an important part of the campaign, because they really do have a difference of opinion on things," said Jewett. "But gosh, right now it just shows no sign of letting up as far as personality and character assassination."
A poll of registered voters conducted April 27 to May 8 by Quinnipiac University showed Murphy doing slightly better against the Republican field than Grayson. But pollsters have found that none of the candidates —- Republican or Democrat —- seeking to replace Rubio are particularly well-known by voters.
The Republican Senate primary contest hasn't been without its own warts, but much of the media attention has focused on the Democrats.
The National Republican Senatorial Committee, which would prefer to face Grayson in November because he is expected to have a tougher time swinging votes north of Orlando, has already started tossing negative ads at Murphy.
It remains to be seen how the attention, good or bad, will play for the Democratic primary winner.
Jewett said that while some think any publicity may be better than no publicity, the winner of the Democratic slugfest could be left with exceedingly high negatives that turn off the voters.
"Definitely right now I'm pretty sure that the Democratic candidates are more well-known to the average general-election voter," Jewett said. "But whether over a few months, if the really high level of negative and personal attacks continue from both sides, then certainly their reputations are going to take a hit."
A big part of the early campaign, besides collecting money, has been about sound bites and winning brief cycles on social media.
Grayson on Thursday blamed Murphy for running an "issue-phobic smear campaign" and reporters who fall for the ploy.
Galia Slayen, a Murphy campaign spokeswoman, said the campaign has introduced platform pieces, such as a 12-page "roadmap" to help Florida families. But it can't control the focus of the media.
In other words, the media can focus on buzzwords like "crook" and "Trump of the left" or delve into discussions of fair trade, college affordability and housing.
But the candidates know the buttons to push for social media and more-traditional media.
Grayson is a master at attracting attention by attacking Republicans, including using a widely repeated line that the GOP's health-care plan is, "Don't get sick." On Thursday, he altered that line to address a congressional fight about funding to fight the Zika virus. Grayson said Republicans' Zika defense is, "Don't get bit."
Murphy held a telephone press conference Thursday in which he responded to questions about immigration while receiving the endorsement of a Democratic Congressional Hispanic Caucus PAC. During the call, Murphy said the "sort of strident anti-immigrant rhetoric from Donald Trump —- it's just so dangerous."
Within an hour, an online newspaper blog headline announced that Murphy "slams Donald Trump."
Congressman Alan Grayson has long mocked his U.S. Senate primary opponent Patrick Murphy as not being a true Democrat.