While Texas has traditionally been a dependable red state, Democrats believe they have a real shot at ousting incumbent Republican Senator Ted Cruz.

Candidate Beto O’Rourke, 46, is hoping to be part of a “blue wave” sweeping the country in November’s midterms and has made a strong impression on the campaign trail.

Here’s our introduction to one of the defining election races of the autumn.

Who are the candidates?

Mr O’Rourke, who hails from El Paso, has called for the impeachment of Donald Trump and expressed his admiration for NFL star Colin Kaepernick’s divisive “take a knee” national anthem protest, regarded by some as unpatriotic and disrespectful but encouraged as a symbol of healthy debate by the candidate.

“I can think of nothing more American than to peacefully stand up, or take a knee, for your rights, anytime, anywhere, anyplace,” he said, concluding a thoughtful and eloquent address touching on the Civil Rights Movement and Black Lives Matter.

His reasoned, progressive example has seen his party’s voter registration double and his campaign break fundraising records, building an impressive $39m (£30m) war chest from small grassroots contributions while rejecting donations from wealthy lobbying interests.

His chances of success at the polls will depend on his ability to appeal to the Lone Star State’s Hispanic population, first-time voters and those who typically sit-out statewide ballots but do come to the polls every four years for presidential elections.

Texas Republicans have, however, are fired up for the midterms and ready to back Mr Cruz, 47, in the wake of the heated Brett Kavanaugh confirmation hearings, with many incensed by the treatment of President Trump’s preferred candidate for the bench after sexual assault allegations were made against him.

They also take exception to out-of-state support for Mr O’Rourke from the likes of comedy producer Judd Apatow, staging stand-up shows to raise money for the Democrats’ golden boy in California.

Mr Cruz currently enjoys a 37 per cent approval rating among Hispanics, according to Quinnipiac University findings, the demographic reassured by his Catholic faith even if they do not share his hard-line approach to the Mexican border.

Senator Cruz’s defeat represents a Herculean task but would mean a major personal humiliation for the former would-be presidential candidate if it could be accomplished.

US midterm elections: the voters Show all 10 1 /10 US midterm elections: the voters US midterm elections: the voters Ross Kershey of Exton, Pennsylvania objects to President Trump's recent threat to unilaterally suspend the constitutional protection of birthright citizenship as a way to control undocumented immigrants AP US midterm elections: the voters Thomas Jakel of Eveleth Minnesota is a former miner. The economy is the most important thing to voters in his town AFP/Getty US midterm elections: the voters Jerry Mcneff of Exton, Pennsylvania intends to split his ballot between the parties for Pennsylvania's House, Senate and governor elections AP US midterm elections: the voters Jean Hoffman of Exton, Pennsylvania has concerns about the cost of her daughters' college education. She thinks that voting Republican might help extend the economy's rise AP US midterm elections: the voters Supporters attend a rally of President Trump in Rochester, Minnesota AFP/Getty US midterm elections: the voters Supporters attend a rally of President Trump in Rochester, Minnesota Reuters US midterm elections: the voters Supporter Jenny Haley and son wait in line to see a Trump Rally in Rochester, Minnesota AFP/Getty US midterm elections: the voters Dick Calef of Exton, Pennsylvania is a life-long Republican. He credits the economic gains in suburban Philadelphia to longer-term factors beyond Trump's policies, such as the growth of internet and health care companies. He's not yet sure how he will vote AP US midterm elections: the voters Markus Fasel of Mendota Heights, Minnesota attends a campaign event for Democrat Angie Craig, his favoured congressional candidate AFP/Getty US midterm elections: the voters Supporters attend a rally of President Trump in Rochester, Minnesota Reuters

What are the key issues?

Immigration and abortion will be key topics of contention, with Mr O’Rourke confronted by a conservative heckler at a debate in San Antonio, who angrily accosted him over his beliefs. “I believe in a woman’s choice,” was his calm response.

Access to healthcare will be another important issue, Texas being one of the least insured states in the union.

Voters’ attitudes towards President Trump will certainly be an important factor.

Despite regularly deriding him as “Lyin’ Ted Cruz” when the men were rivals for the Republican presidential nomination in 2016, the president has now given his backing to Mr Cruz, praising him on Twitter for boosting the state’s employment statistics through “massive cuts in taxes and regulations”.

The idea the duo have buried the hatchet suggests a remarkable capacity for forgiveness from Mr Cruz, given that Mr Trump’s mudslinging extended to sharing an unflattering picture of the Texas politician’s wife Heidi on social media and accused his father, Rafael Cruz, of being an associate of Lee Harvey Oswald and having a hand in the assassination of JFK.

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Mr Cruz has supported the president’s “zero-tolerance” policy on illegal immigration but also worked to ensure families separated at the border are reunited.

His subsequent acceptance of the president’s backing has been roundly mocked by his opponents. The Texan film director Richard Linklater has even filmed a promotional video on behalf of the Fire Ted Cruz Political Action Committee to ridicule the candidate’s perceived hypocrisy.

President Trump has meanwhile inevitably attacked Mr O’Rourke as “lightweight” and “a flake”.