US President Donald Trump fires up his supporters at a campaign rally in Johnson City, Tennessee, as his Republican party girds for a Democratic wave in next month's midterm elections
Washington (AFP) - Americans head to the polls one month from Saturday, and a blue wave alert is sounding from coast to coast.
US presidents traditionally see their party lose seats in Congress in the first election after they take office, and for Donald Trump this year is likely to be no exception.
The question is, can Republicans maintain their majorities in the Senate and House of Representatives? The answer might hinge on these key races:
- Democrats mess with Texas -
The Lone Star state is hosting the most closely watched -- and most expensive -- Senate race this year, with Beto O'Rourke, a punk rocker-turned-congressman who espouses health care for all, criminal justice reform and stronger gun-safety laws, taking on popular incumbent Senator Ted Cruz.
Beto, as supporters call him, has already campaigned in all 254 counties. He rules in the big cities, but there is a lot of conservative country out there that Beto would need to win over.
Flipping deep red Texas has been a Democratic dream for years. They will need suburban anti-Trump anger to help them pull off such a political earthquake with national repercussions.
- Republicans eye Midwest steal -
Missouri is a prime Republican pick-up opportunity as they target vulnerable two-term Senate Democrat Claire McCaskill.
The Midwestern state has tilted steadily conservative in recent years, and Trump won it by 19 points over Democrat Hillary Clinton in 2016.
Republican Josh Hawley is polling neck and neck with McCaskill, and Trump has campaigned for Hawley, calling him a "star."
Should Republicans steal Missouri -- or North Dakota or Indiana, where Senate Democrats are defending seats in Trump country -- the party is likely to retain its Senate majority.
- GOP wall in southern Florida? -
Hillary Clinton won Florida's sprawling 26th district south of Miami by 16 points in the 2016 presidential election, but Democrats face a tough task in ousting incumbent Carlos Curbelo.
The Republican with a Hispanic background has frequently criticized Trump, excoriating him earlier this year for meeting privately with Russian President Vladimir Putin.
Experts say Curbelo's position could help him weather the blue wave in the battleground district and defeat Democrat Debbie Mucarsel-Powell.
Another Florida battle royale is shaping up as Democrat Andrew Gillum, the mayor of Tallahassee, aims to become the state's first black governor.
He's facing Trump acolyte Ron DeSantis, who made what many believe to be racially coded remarks when he warned voters not to "monkey this up" by embracing a far-left agenda.
- Duel in the desert -
Arizona's District 2 hugs the US border with Mexico, and Trump's immigration policy will play a pivotal role as voters decide between Republican Lea Marquez Peterson, a Hispanic community leader, or Democratic former congresswoman Ann Kirkpatrick.
Marquez Peterson is a GOP woman running for Congress in the Trump era, but she has said she manages to "separate the man from the policy."
The seat's outgoing occupant, former fighter pilot Martha McSally, is running for the Senate in another marquee battle that features two female candidates.
- Spotlight Minnesota -
The north-central state of Minnesota finds itself in a rare political position in 2018: front and center.
Throughout the country only two Democrat-held seats are toss ups, according to Cook Political Report. Both are in Minnesota.
They include District 8, once a Democratic stronghold that has shifted from blue to purple. Key issues in the open-seat race between Democrat Joe Radinovich and hockey player Republican Pete Stauber could be Trump's trade wars, and the simmering resentment of older voters whose timber and Iron Range jobs left years ago.
Meanwhile two Republican congressmen are fighting for their political lives in Democrat-leaning Districts 2 and 3.
- Heartland in play -
With Democrats enjoying demonstrable grassroots intensity, the party's push into Republican territory has made its way to heartland Kansas and its all-Republican congressional delegation.
Sharice Davids, a gay Native American mixed martial arts fighter, is challenging Republican congressman Kevin Yoder for his District 3 seat.
Yoder became deeply vulnerable this week, when the House Republican campaign arm pulled its advertising support, signaling a hostile election climate for Republicans.