The march to the US midterm elections, which will determine which party controls both chambers of Congress for the second half of Donald Trump's presidency, is officially under way.

Voters in a handful of states headed to the polls on Tuesday to pick the Democratic and Republican candidates for the November general election.

It was Texas, and contested primary races for a US Senate seat, that attracted the lion's share of the attention. The races in the southern state could shed light on the directions that America's two major parties are taking in the coming election season.

For the Democrats, state representative James Talarico defeated Dallas-based US Congresswoman Jasmine Crockett and will advance to the general election. The Republican race was not decided on Tuesday, as Texas Attorney General Ken Paxton and US Senator John Cornyn, the incumbent, each finished with less than 50% of the overall vote. The two men will advance to a run-off election on 26 May.

Here are five takeaways from the voting in Texas - in what is just the start of months of primary campaigning across America.