Keir Starmer has said he wants to meet Kamala Harris and Donald Trump before the US election, as he declined to back one of his ministers who said the Republican candidate had contributed to racist rhetoric in the UK. The prime minister said he was hoping to find time with both candidates as he travelled to New York for the United Nations general assembly – his third trip to the US since taking office. “If possible, it would be very good to meet both of them at some stage before the election. We’ll just have to see what’s possible,” he said, speaking on his flight after the Labour conference. Starmer is understood not to want to see one candidate without also meeting the other, despite Labour’s closer links with the fellow centre-left Democrats in the US. However, Angela Eagle, a Home Office minister, risked undermining No 10’s diplomatic efforts with Trump after saying at a fringe event at Labour conference that his rhetoric had emboldened racists. The new minister for irregular immigration said the Republican presidential candidate had helped to create “vitriol” against migrants through social media. She also said rightwing Tories had used language that had given a “yellow flashing light” to racists, using a “toxic discourse” as they fought off the challenge from Reform UK. Asked about Eagle’s words on Tuesday, a Trump spokesperson reacted dismissively, saying: “Nobody knows who this random person is or cares what comes out of her mouth. Who is she and what does she do?” Starmer did not back his minister when asked on Tuesday whether her words were correct. “I think I’ve been absolutely clear where responsibility lies for the disorder on our streets. It lies with the thugs who were carrying out that disorder. That’s why I took control of the process to ensure that justice was visited very quickly on their cases,” he said. The prime minister is heading to the UN summit fresh from his speech at the Labour conference, admitting on Tuesday night that he was “absolutely knackered”. At the assembly in New York, the Ukrainian president, Volodymyr Zelenskyy, will be pushing for a deal on the use of Storm Shadow missiles against Russia, supported by the UK. Zelenskyy is expected to meet both Harris and Trump during his visit to the US as part of efforts to present a “victory plan” that maps out a path to defeating Vladimir Putin. Asked about Zelenskyy’s prospects of success, Starmer told reporters it was “at a critical stage”. “Obviously, President Zelensky has a plan that he wants to walk through with all of us … The support for Ukraine is resolute. We supply quite a lot of capability already under the last government; we’ve increased that under this government – that’s not a criticism of the last government – and we will always listen very carefully to what Ukraine says it needs by way of capability.” He said the long-range Storm Shadow missiles would not be the sole issue under discussion but it would also be about “the strategic overarching route for Ukraine to find a way through this and succeed against Russian aggression”. Starmer’s trip is taking place as negotiations continue with the White House to allow Ukraine to use long-range weapons on Russian territory. David Lammy, the UK foreign secretary, argued this week it was time for “nerve and guts” to allow a change of policy. But Starmer’s visit to Washington to see the US president, Joe Biden, earlier this month did not resolve sticking points over the use of the British and French-made weapons, which also rely on US technology. Even if a breakthrough is made on the talks this week, it is unlikely any decisions on the missiles will be announced at this week’s summit. The British prime minister will give a speech to the UN summit on Thursday, arguing that taking an international lead on war, climate change and poverty will stop issues “rebounding” on to the UK, such as “migration flows on an unprecedented scale”. Starmer is expected to have bilateral meetings with a number of world leaders, and to also meet chief executives during his two-day visit to New York.