Hello and welcome to the US politics live blog.

Texans are voting for a Republican nominee for US Senate in Tuesday’s runoff election, following Donald Trump’s late bid to influence the race in his latest effort to rid the GOP of less devoted leaders.

The president’s endorsement of state attorney-general Ken Paxton over four-term senator John Cornyn gave the challenger a late boost, leaving Cornyn at risk of becoming the first Republican senator in Texas history to seek the party’s nod and lose.

It comes despite Cornyn’s campaign and allied groups spending roughly $90m in advertising since last year, the vast majority of it attacking Paxton, AP reported.

It’s the latest GOP contest where Trump has sought to punish a Republican he sees as insufficiently loyal. This month, he has successfully backed challengers to incumbents in Louisiana, Kentucky and Indiana – a sign of his enduring influence among primary voters.

Paxton’s campaign and a pro-Paxton super PAC began airing ads promoting the endorsement within 24 hours of Trump’s announcement. Cornyn acknowledged Trump’s move would have an impact but said he wasn’t giving up.

“I know who gets to choose our senators, and it’s the people of Texas,” he said hours after the endorsement. The winner will run in November against the Democratic candidate James Talarico .

Tuesday’s runoffs also will decide Democratic US House nominees for districts in Dallas and Houston that overwhelmingly support Democrats and a San Antonio-area seat the party hopes to flip.

In other developments:

• Iran has poured cold water on suggestions that a deal with the US is imminent, pointing to the confusion in US positions and Israeli interference as reasons why an agreement is proving difficult to secure. Speaking at the weekly foreign ministry press briefing, Esmail Baghaei, the spokesperson for Iran’s negotiating team, also said future management of the strait of Hormuz was a matter for Oman and Iran to agree on, and that it was not tolls that were being proposed but “fees for navigational services”.

• By contrast, the US secretary of state, Marco Rubio, said that a deal was still possible, adding that the strait of Hormuz would open “one way or another”. “There were some talks going on in Qatar today, so we’ll see if we can make progress. I think it’s a lot of talking back and forth going on about specific language in the initial document,” Rubio told reporters in Jaipur during an official visit to India.

• A Trump Tower planned for the Georgian capital, Tbilisi, is to be built on land currently part-owned by the son of the US-sanctioned leader of the country, according to official records. The proposed skyscraper, a joint venture between a local consortium and the Trump Organization, which is managed by the US president’s sons, Donald Trump Jr and Eric Trump, will be on a plot whose current registered owner is the International Charity Fund Cartu.

• Mexico’s president, Claudia Sheinbaum, said on Monday her government agreed to allow the Iranian national football team to stay in Mexico during the World Cup, adding that the United States did not want to host the team. Sheinbaum said football’s governing body Fifa approached her government after the US said it did not want Iran’s squad to stay in the country throughout the tournament, despite Iran playing all three of its group matches there.