And in Tennessee, Congresswoman Marsha Blackburn defeated former Gov. Phil Bredesen, a top Democratic recruit. "You're going to see the largest gender gap we've ever seen".
Anxious Republicans privately expressed confidence in their narrow Senate majority but feared the House was slipping away.
Florida is living up to its history as a cliffhanger state, with Democratic Sen. Polls suggest Democrats, but President Donald Trump proved with his presidential victory that such data is fallible. Voters in the 2nd District supported Trump by less than 2 percentage points in 2016.
Addressing his supporters, he said, "The key is you have to go out to vote because in a sense I am on the ticket".
"I think we're going to do well in the House", he said of Tuesday's races.
He bet big on a xenophobic closing message, warning of an immigrant "invasion" that promised to spread violent crime and drugs across the nation.
NBC, Fox News and Facebook pulled an ad by President Donald Trump's campaign that critics had labelled racist as a bitter election fight for control of the U.S. Congress headed on Monday for an unpredictable finish.
The president's current job approval, set at 40 percent by Gallup, was the lowest at this point of any first-term president in the modern era. Right now the GOP has a 51 seat majority. Some are considered vulnerable, as they are in states won by Mr Trump when he was elected in 2016. Menendez is being challenged by Republican businessman Bob Hugin, 64. What was not normal was that Menendez had been indicted on corruption charges and escaped with hung jury. Democrats would very much like to demonstrate good results there, especially to create momentum for the next presidential election. There are 47 Democrats, and two independents who caucus with the Democrats.
In south Florida, former Health and Human Services Secretary Donna Shalala defeated Republican Maria Elvira Salazar.
After Ohio, Trump headed to campaign against vulnerable Democratic U.S. senators in IN and Missouri at the end of a six-day pre-election sweep that has featured heated rhetoric about immigration and repeated warnings about a caravan of Central American migrants moving through Mexico toward the U.S. border.
At stake are all 435 seats in the House of Representatives, 35 seats in the 100-member Senate, 36 governor's posts and seats in state legislatures across the country.
Besides stymieing the Trump agenda, a Democratic victory in the House could allow Democrats to launch multiple committee investigations of the Trump administration and possibly even impeachment proceedings.
He and the first lady were to host an evening watch party for family and friends. The most important advantage Republicans have is geography.
Some Democrats have already vowed to force the release of his tax returns. Considering where in the country results have been returned, the make-up of the two chambers before the elections and what was expected, our political and data team will make a call on which of the five emotions we reckon Trump will be feeling at that time.
For the Democrats, that means an appeal to the reliable demographics such as young people, college-educated older people, and minorities. But one of the Democrats, Lyman Hoffman, joined the Republican leadership.
Nevertheless, it remains to be seen whether this tactic will help GOP candidates.
The demographic divides were coloring the political landscape in different ways.
Democratic House leader Nancy Pelosi said Democrats in the US House of Representatives will use their newly won majority to pursue a bipartisan agenda for a country that she said has had "enough of division".
Trump also could face more pushback from Democrats on trade tariffs he has introduced, particularly in farm states hard hit by retaliatory measures from China or manufacturing states hit by higher steel and aluminium prices.
Some Georgia voters saw lines of hundreds of people waiting to cast ballots in an election that will determine control of both houses of Congress and three dozen governors' seats.
Democrats boasted record diversity on ballots.