Hillary Clinton faces critical decision as she mulls running mate options

Four weeks from now the Democrats will be converging on Philadelphia for their convention and the chatter will be all about the person that Hillary Clinton will by then - we assume - have picked to be her running mate. The guessing game, of course, is already in full swing.

If all eyes seem suddenly to be on Elizabeth Warren, the US Senator from Massachusetts who is beloved by the progressive flank of the party, it is because on Monday she was on the road with Ms Clinton for a rally in Ohio, a key swing state. But there are some other persuasive names also swimming in the campaign ether. Here they are:

Known to be on the campaign shortlist and subject already to vetting are:

Senator Elizabeth Warren: A former defender of financial consumer rights appointed by President Barack Obama and now in her first term as a US Senator, Ms Warren is the nearest thing to Senator Bernie Sanders that Sanders supporters are likely to get now that he has conceded the nomination will not be his. Monday’s rally in Cincinnati was a chance for Ms Clinton to do a chemistry check with the Senator to figure out how well they mesh.

Julian Castro: the Secretary of Housing and Urban Development, Mr Castro would offer a bright and shiny contrast to the sometimes wooden Ms Clinton. The former Mayor of San Antonio in Texas, the seventh largest city in the US, he is only 42 years old. She will be 69 on election day. His another big draw: he is Hispanic and would help her consolidate support in the Latin community. On the other thand, his Texas base won’t help much. Texas won’t go blue in November.

Tim Kaine: the former mayor of Richmond, Virginia, and former governor of the state, Mr Kaine may be tempted to Ms Clinton because of his steadfastness. There isn’t much risk in choosing him. Indeed in an interview with NBC at the weekend, he described himself as pretty boring. Now a US Senator, he also has the advantage of coming from an absolutely key swing state that Barack Obama won in 2012 but which still has a very strong Republican streak.

Also possibly up for consideration:

Tom Perez: the US Secretary of Labour, is seen as the Hispanic alternative to Mr Castro. But he has less youthful appeal. It could be, however, that Mr Trump’s success in alienating the Hispanic vote so effectively, makes the diversity case less important in choosing a Veep.

John Hickenlooper: the popular Governor of Colorado, Hickenlooper also has geographic appeal as Ms Clinton must hold to recent gains in the Rocky Mountain states to maximise her chances of securing the White House.

Sherrod Brown: the US Senator from Ohio is a longtime friend of Ms Clinton and there seems little doubt that the two would fit well together as a team, both campaigning and when/if it comes to running the country. And Ohio is the swing state to end all swing states. A rather gruff figure, Brown has good blue-collar credentials and a reputation for standing on the liberal wing. He got a shout-out from Ms Warren in Cincinnati.

Amy Klobuchar: the Senator from Minneapolis is the other ‘woman’ possibility, if Ms Clinton decides that an all-female ticket is what she wants. An ambitious figure on the Hill, she has worked hard to support Ms Clinton and, most importantly, has her a strong Midwest base.