Keir Starmer is planning to wait until after the US election to name a new ambassador to Washington, sources have told the Guardian, as the prime minister wants to see who the next president is before making his pick. Labour has been considering a political appointee, such as Cathy Ashton, David Miliband or Peter Mandelson, to be the country’s representative to the US. Ministers have decided not to appoint Tim Barrow, the outgoing national security adviser, whom the Conservatives had chosen for the role shortly before the election. With Joe Biden floundering, however, and Donald Trump ahead in the US polls, ministers now want to see who wins the November election before making a decision. Starmer is to meet Biden this week for the first time at the White House as he travels to Washington for a Nato summit of world leaders. Officials say Starmer is considering reappointing the current ambassador, Karen Pierce, who has a good relationship with Trump and is a frequent guest on Fox News. Starmer’s choice will be one of the most important diplomatic decisions he makes in his first year in the job, and is likely to shape UK-US relations for the next four years at least. One official said: “The big dilemma for Starmer will be whether to make a political appointee or a more routine civil service appointment. He’s going to wait until after November to see who is in the White House before he makes that decision.” Another said the government had begun a recruitment process for the post and aimed to have someone in place by 25 January, when Pierce’s first term ends. Bronwen Maddox, the chief executive of the Chatham House foreign policy thinktank, said: “This post really matters – it is one of those diplomatic posts that really forges the relationship between the two countries.” She added: “It is a relationship with Congress as much as it is with the president, and that is something that is not accessible to the prime minister. It is not like a relationship with a European country, much of which can be handled over the phone.” Rishi Sunak’s government had decided to replace Pierce with Barrow, much to the chagrin of Labour officials, who wanted the chance to make their own choice. Barrow’s appointment was in effect suspended by the general election, allowing Starmer and the foreign secretary, David Lammy, to start the process from scratch. Barrow has now been told he will not be getting the job. Several high-profile names were reported to be in the running for the job, including Ashton and Mandelson, both former EU commissioners, and Miliband, the former foreign secretary. Simon Fraser, a former head of the diplomatic service, is also believed to be in the frame. However, many of these candidates are unlikely to curry favour with a new Trump administration, given either their links to the Labour party or their backgrounds as civil servants. Trump is about two points ahead in the polls, while Biden is under pressure from his party to quit the race after his recent disastrous televised debate performance. The former president demanded the resignation of Pierce’s predecessor, Kim Darroch, after a leaked diplomatic cable showed Darroch calling his administration “uniquely dysfunctional”. Trump does have a good relationship with Pierce, however, and was reported to have spoken glowingly about her to Boris Johnson when Johnson was prime minister and Pierce was the UK ambassador to the UN in New York. Pierce is also seen in Labour circles as someone who “can do Fox News”, which has previously proven one of the most effective ways of capturing the former president’s attention. Pierce is known to be keen to stay in post, even if not for a full second term, and reportedly told an event in Washington last spring that she would “have to be dragged out of here by my fingernails”.