Campaigning for midterm elections has begun in the US, including in Texas, where voters choose between Beto O’Rourke, a Democrat, and the incumbent senator, Ted Cruz, a Republican and former presidential candidate.

The contest between the two men, which was finalised on Tuesday night, has been used to demonstrate that Texas, a conservative state that has not elected a Democrat in a statewide position since 1994, might be in play for the liberal Democratic Party.

Midterm elections to decide the make-up of the country's legislature will be held in November this year. A total of 469 seats will be up for grabs in both the Senate and House of Representatives.

Controversy has arisen around the names of the candidates as Cruz, a staunch conservative and Catholic, unveiled a political advertisement featuring a song accusing O'Rourke - who uses a common Latino first name, although he is not of Latino descent - of changing his name to win voters.

"Little Robert wanted to fit in, so he changed his name to 'Beto', and hid it with a grin," the song claimed.

O’Rourke has said that the name "Beto" is a common nickname for those named Robert in his hometown of El Paso, Texas.

The Democratic candidate posted a photograph of himself as a baby wearing a sweater with "Beto" stitched on the chest.

But O'Rourke is not the only name-changing candidate in the contest.

Cruz's given name is Rafael Edward Cruz, although he goes by "Ted", a name commonly used by white Americans.

O'Rourke has not commented on Cruz's choice of name.

Favourability ratings

Though most polls and political analysts believe Cruz still has the edge over O’Rouke, there are signs that he could lose.

Democrats feel more confident this election season due to the continued unpopularity of President Donald Trump.

Favourability ratings for Trump, a Republican, hover near 40 percent, nationally.

The president is equally unpopular in Texas.

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Republicans have lost elections in other conservative states where Trump is unpopular.

Cruz is also unpopular among voters, according to the Texas Politics Project (TPP), a part of the University of Texas that conducts public opinion polling.

As of February, about 42 percent of Texans viewed him as favourable while 31 percent of respondents considered Cruz "very unfavourable".

Another 12 percent said they did not view him favourably or unfavourably.

Cruz's favourability rating was placed at 40 percent by TPP.

Nationally, Cruz's approval ratings are in the single digits.

Most Texans do not have as firm an opinion about O’Rourke as they do Cruz, who has served as a senator for the past six years, TPP polling shows.

Still, O'Rourke is gaining steam on Cruz in terms of fundraising.

In the last three months of 2017, the O'Rourke campaign raised $2.4m while Cruz raised $1.9m. It was the second time O’Rourke outraised Cruz.

While O'Rourke has won in recent fundraising quarters, Cruz still has the overall advantage.

The incumbent raised $7.1m in 2017 to O’Rourke's $4.6m.