Democrats have pulled ahead in Florida's marquee races for the U.S. Senate and governor, a new Reuters opinion poll showed on Wednesday, as President Donald Trump returned to the battleground state in a closing bid to bail out Republicans.U.S. Senator Bill Nelson is leading Rick Scott, Florida's Republican governor, by 5 percentage points among likely voters, according to the Reuters/Ipsos/UVA Center for Politics poll.A win by Nelson would be critical for Democrats' hopes of taking a majority in the Senate, which would require a net gain of two seats in the Nov. 6 elections. Most opinion polls and forecasters give Democrats a slim chance of winning control of the chamber, because they have to defend 10 seats in states that Trump won in 2016, including Florida.Addressing a crowd in Estero, Florida, Trump reeled off his usual attacks on the Democrats, saying they stood for high taxes, crime, open borders and uncontrolled immigration.It was the first stop on a six-day, eight-state, 11-rally tour that will bring Trump to eight states, including Missouri, Indiana and Tennessee, which are also home to hard-fought Senate races.Democrat Andrew Gillum, the Tallahassee mayor, is holding on to momentum in his bid to become Florida's first black governor. He drew the support of 50 percent of likely voters, unchanged from the last Reuters polling a month ago, compared with 44 percent supporting former U.S. Representative Ron DeSantis."Ron is running against a radical socialist who wants to turn Florida into Venezuela," Trump told his supporters.Gillum's candidacy may be boosting a Democratic ticket that includes Nelson, who has opened up a significant lead in a Senate race that was tied last month in another Reuters/Ipsos poll. In the latest poll https://tmsnrt.rs/2piev5l, 49 percent of likely voters said they would return Nelson to Washington for a fourth term in the Senate, while 44 percent wanted to replace him with Scott.The Democratic strength at the top of the ballot could affect as many as a half dozen competitive contests across Florida for the U.S. House of Representatives. Democrats are seen as having a strong chance of winning at least the 23 seats needed to gain control of the House, and with it the power to derail Trump's agenda.Seeking to drive up turnout by his core supporters, Trump in recent weeks has tossed out a rapid-fire set of policy proposals: Sending up to 15,000 troops to the border with Mexico to address illegal immigration, calling for a 10 percent tax cut and floating a plan to reverse a guarantee of citizenship for everyone born in the United States."This is a referendum on Donald Trump," said Aubrey Jewett, a political science professor at the University of Central Florida, noting that Trump's reputation rode on a governor's race where his endorsement delivered the Republican nomination to DeSantis. "If DeSantis loses, that is a direct reflection on Donald Trump in Florida and the power and influence that Trump has over Florida voters currently."Although Trump narrowly won Florida in the 2016 election, 51 percent of likely voters in the state now disapprove of how he is handling the presidency, according to the new Reuters poll.Oprah Winfrey, whom fans early this year tried to lure into taking Trump on in a 2020 White House run, is due in Georgia on Thursday to campaign with Democrat Stacey Abrams, who is seeking to become the United States' first black woman governor.SENATE BATTLEFIELDThe Reuters poll painted a brighter picture for the Republican slate in Arizona, where two U.S. congresswomen are battling for the Senate seat being vacated by Jeff Flake, a Republican who has been a prominent Trump critic.Republican Martha McSally leads Democrat Kyrsten Sinema by 2 percentage points, according to the new Reuters poll. Sinema led a Reuters poll last month.A NBC News/Marist poll released this week showed Sinema with a 6-point lead.The Reuters poll showed the state's Republican governor, Doug Ducey, on track to win his re-election fight, with a 20-percentage-point lead over Democrat David Garcia.Florida Democrats are trying this year to turn out more young and diverse voters, who lean Democratic but often sit out midterm elections. Leaders in the party hope Gillum's candidacy will see a repeat of the voting coalition that enabled former President Barack Obama to carry the state twice, before it swung for Trump.Obama will stump for Gillum and Nelson in Miami on Friday.The Reuters/Ipsos/UVA poll was conducted online, in English, from Oct. 17 to 26. It surveyed at least 799 likely voters in each state and had a confidence interval, a measure of accuracy, of 3 percentage points in Florida and 4 points in Arizona.The poll results measured how voters felt at the time of the survey. Those feelings may change: In 2016, one in eight Americans reported making the presidential pick in the week before Election Day, according to a Reuters/Ipsos poll.