Buchanan has represented the Congressional District centered on Manatee and Sarasota counties for 20 years. That longevity has undoubtedly chased away countless challengers.
That's not true anymore.
Nine candidates have filed to run - three Republicans, five Democrats and one with no party affiliation.
St. Leo University political scientist Frank Orlando said the eventual winner is likely to be a Republican, based on the district's voting history. And the favorite is Sydney Gruters, who has been endorsed by President Trump.
"Gruters has all the institutional support on this," Orlando said. "Her husband (Joe Gruters) is the RNC chair. She has all the backing. She's spent the most money. Would be difficult to see an anti-Gruters vote. It's a three-way race (with Ed Pope and Eddie Speir), although there's probably two front runners, but I would say Gruters to me is the favorite."
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The Democrats are led by former Sarasota Mayor Kelly Kirschner and Jan Schneider - who has repeatedly lost to Buchanan. Orlando said that experience on the ballot may not translate into her winning Tuesday's primary.
"Just because someone has been a candidate many times in a row doesn't give them an advantage. It just means that it wasn't appealing to high quality Democrats in the past," Orlando said. "In an open seat with a little bit of shifted lines, that piques the interest of quality Democratic candidates. And so, to me, when you've got mayoral experience in Sarasota, you're much more likely to jump into this race, and I think that would be my prediction."
He says even though the district now includes very blue St. Petersburg, it still leans Republican. And Buchanan has repeatedly won more than 60% of the vote.
"It's a huge uphill climb (for Democrats)," he said. "On average, this is about a district that reflects the breakdown of the state in terms of how much Trump won it by versus how much you won this district by, and so you would need a huge over-performance to win."
