The US is to send distinctly low-key official representation to Lady Thatcher's funeral on Wednesday, with a delegation led by George Shultz and James Baker, who both served as US secretary of state while Thatcher was in power.

While Barack Obama was invited, he has opted to send a presidential delegation comprising no serving politicians. Shultz was secretary of state to Ronald Reagan while Baker served the elder George Bush. Also representing Obama will be Barbara Stephenson, chargé d'affaires at the US embassy in London, and Louis Susman, the recently departed ambassador to Britain.

Separately, the Republican party is sending three members of the House of Representatives: Marsha Blackburn, who will lead the delegation, along with Michele Bachmann and George Holding. Blackburn is a leading fiscal conservative, while Bachmann, a member of the hardline conservative Tea Party faction, became internationally known during her spectacular if brief bid for the 2012 presidential nomination.

Another leading Republican conservative and attempted 2012 nominee, Newt Gingrich, is also among the confirmed attendees. Ronald Reagan's widow, Nancy, was invited but has said she felt unable to make the trip aged 91.

The somewhat ambiguous nature of Thatcher's funeral, which is not a state event but nonetheless has many of the trappings of such a ceremony, given the involvement of the Queen and members of the armed forces, has prompted a varying response from other countries in terms of representation.

While some are also sending former leaders, for example Australia's John Howard, several serving prime ministers have said they will attend, including Stephen Harper of Canada, Italy's Mario Monti, and Donald Tusk from Poland.