Washington(CNN) Democrats picked off another Republican-held state legislative seat in a special election Tuesday -- this time a suburban, Sarasota-area district in Florida.

Margaret Good's win over James Buchanan -- the Republican whose father is US Rep. Vern Buchanan -- is another worrying sign for national Republicans headed into next fall's midterm elections.

Good won by 7 percentage points in a district that President Donald Trump carried by 5 points in the 2016 election.

That swing in Democrats' direction made the Florida contest the 36th GOP-held state legislative seat to change parties since Trump took office. And in a district where Republicans held a voter registration advantage of nearly 13,000, the Democratic Party sees it as evidence it can win in Republican strongholds.

It's far short of the nearly 1,000 seats Republicans won during former President Barack Obama's tenure, but Democrats see the wins as signs of an energized base that could deliver control of the House, and potentially the Senate, to the party in this year's midterm elections.

It was the third straight loss for Florida Republicans in contests seen as bellwethers for the midterms. Democrats won a Miami-area state Senate special election last September with Annette Taddeo, then won the St. Petersburg mayoral race in November.

Unlike some other Trump-country victories for Democrats in recent weeks -- including wins in Wisconsin and Missouri -- the Florida contest was an intense battle.

It's a growing, suburban district, much like the areas where other states have seen the biggest swings in Democrats' favor.

Good was backed by the Democratic Legislative Campaign Committee and endorsed by former Vice President Joe Biden.

Her win comes as Republican Gov. Rick Scott considers whether to challenge Democratic Sen. Bill Nelson ahead of a March filing deadline.

"Just like we did last year with Annette Taddeo, Democrats are organizing, investing and winning elections across Florida as voters reject Rick Scott and Donald Trump's disastrous agenda," said Democratic National Committee Chairman Tom Perez.

Former Trump campaign manager Corey Lewandowski and deputy campaign manager David Bossie campaigned there over the weekend, just before Tuesday's contest. They led a Sunday rally where the crowd, echoing the Hillary Clinton-bashing Trump campaign of 2016, chanted, "Lock her up!"

"Let me just say this: You guys have an election on Tuesday," Lewandowski told a crowd Sunday, the Sarasota Herald-Tribune reported. "The fake news is going to watch you. The failing New York Times wants to write that James Buchanan lost the seat and that Donald Trump cannot carry a candidate anymore. That's what they want. You cannot allow it."

"The Democrats are highly motivated," Lewandowski said. "They are winning elections in places where they shouldn't ... 50 seats have already changed hands from the Republicans to the Democrats since Donald Trump was elected. That should be concerning for us. Dave and I are here to make sure that one thing happens: that Buchanan goes to the state House and we don't have another Democrat in office."