Joe Biden told us long ago he would pick Kamala Harris – now we know why

In the end, Joe Biden, mindful of his 78th birthday in November, did exactly what he said he would by picking the running mate he felt was best-suited to take over as president.

California Senator Kamala Harris will join the former vice president on the top of the Democratic ticket, positioning her to potentially become the first female, black US president should Mr Biden be unable to continue, if elected, for health reasons or should he bow out after just one term. Analysts said her tenure as California's top law enforcement official likely led the former vice president to believe she could run the federal government, but they warned her lack of foreign policy experience could be a campaign issue.

Mr Biden, who was a heavily involved vice president whom former President Barack Obama often called a partner, made clear as he secured the party's nomination that he would select someone as his running mate who would both help him win and was someone he felt could step in.

He is 77 years old, and appears in sound physical health; he was caught on camera on Sunday in Wilmington, Delaware riding his bike on a hot summer day.

But the every-four-years drama known as the "Veepstakes" literally decides who would become one major health issue or non-existent heartbeat away from becoming the leader of the free world. Mr Biden would be 78 years old when he would be sworn in, if he can hold his leads over Donald Trump nationally and in key swing states.

But his 77-year-old heart would be days away from being a 79-year-old by the time the 2022 congressional midterm elections roll around.

Enter Ms Harris, a 55-year-old who long has been considered a rising star in Democratic circles.

The former VP recently revealed a major part of his own decision-making criteria, saying he would choose a running mate he deemed "simpatico with me, both in terms of personality as well as substance."

That suggests Mr Biden viewed Ms Harris, who was just one of a long list of national and state lawmakers and governors, as well as a former UN ambassador, as the person he felt would be the best and most-qualified governing partner.

The pick also suggests Mr Biden prioritised readiness to be president over a VP pick who could potentially put one of the key swing states securely in his column.

In Ms Harris, he is getting a former state attorney general from California. That post placed her at the centre of many difficult and complicated legal matters. The two clashed at times during the Democratic primary process, but they both were viewed as domestic and foreign policy moderates when stacked up against progressives like Vermont Senator Bernie Sanders and Massachusetts Senator Elizabeth Warren.

Analysts offered a snapshot of why Mr Biden picked her, suggesting he was impressed by her domestic policy experience and legal background.

The pick could leave the Biden-Harris ticket vulnerable to some criticism, with questions about Ms Harris' foreign policy chops – though the campaign is likely to note that serves on the Senate Intelligence Committee.

"She will be an effective campaigner on his behalf and if elected would bring needed depth to the administration on criminal justice and a wide range of legal issues," said William Galston, a former Clinton White House official. "Yes, she doesn't have a lot of experience in foreign policy, but she would get a crash course during the first year or two as VP, when she would be present at all the meetings and would get to see first-hand how foreign policy is debated and determined.

"Her selection will make most Democrats happy, and unless Biden's vetting team has failed him, there's nothing disqualifying in her background. Some people won't like her, but for the most part they're people who wouldn't have liked any Democrat anyway," said Mr Galston, now with the Brookings Institution. "As far as I can tell, Biden has honoured the political version of the Hippocratic oath: first, do no harm."

Analysts also pointed to her time as state AG, saying that likely impressed Mr Biden by giving him a sense that she could run the country and federal government should be unable to perform the duties of the office, if elected.

"Harris doesn't have the sheer length of service in top-level positions as some other past VP picks – she's only been in the Senate for a little less than four years -- but she does have other top experience as the attorney general of the largest state," said Kyle Kondik of the University of Virginia. "Being an attorney general is, to me, executive experience, so she does have that sort of leadership background (although being president is different than any other executive job).

"She also has run for president, and while her campaign did not go so well, she did get valuable experience and exposure," he added. "She also has been vetted publicly to at least some extent; while one never knows what might come out about a vice presidential pick, many of the other contenders had less public exposure than her."

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