For her sake, and for ours, I hope Hillary Clinton asks Joe Biden to run for a third vice presidential term this fall.

There are several important reasons; the most important one is at the end of this column.

She needs help in dampening the appeal of Donald Trump to white workingmen in key battleground states like Pennsylvania and North Carolina.

Writing about a planned Clinton-Biden campaign trip into Pennsylvania last week, The New York Times correspondent Carl Hulse wrote, “Mrs. Clinton could not have picked a better traveling companion than Mr. Biden. A native son of Scranton, he is wildly popular with voters in Pennsylvania. The Clinton campaign obviously hoped some of his blue-collar credibility rubs off on the presumptive Democratic nominee as she seeks to secure the Democratic hold on the state.”

Biden would be an even better companion if he were on the ticket, assuring voters in places like Pennsylvania that he was not just along for the ride, but would be a part of Clinton’s team for the duration.

Clinton needs a campaign partner who can explain directly, person to person, why the ideas of Donald Trump would not bring an improved life to those working people who might be initially enchanted by his thunderous appeal.

Clinton ought to pick someone who will build enthusiasm in the party base and help overcome doubts of some party regulars.

Some argue that the surprise of a “fresh face” on the ticket would help Clinton most. But these fresh faces, like Sarah Palin, Dan Quayle, and Tom Eagleton, can bring their own sets of disappointing surprises.

Biden may not be perfect. He may be a little shopworn. But he is well known and reliable. He has something no other vice presidential possibility has; he has shown he can help a presidential candidate win.

This presidential election will compare the advantages of turning Washington upside down with Trump against those of stability and strength by continuing the Obama approach. Whether she likes it or not, Clinton’s campaign will rest on showing the advantages of the progressive stability of the Obama presidency. That being the case, she needs someone, with authority, on the ticket, someone who can explain those advantages and persuade voters not to abandon them. To have that someone be the current vice president would be a powerful signal.

A question that has to be asked about every vice presidential nominee: Would he or she make a good successor should something happen to the elected president? Biden’s experience, especially his two terms as Obama’s vice president, makes his claim to readiness compelling.

Of more immediate importance is whether the prospective vice president will be a real help to a new president. By all accounts Biden is a proven effective partner to the president.

Now, the most important reason Clinton should ask Biden to be her running mate: She will need some special help to be a great president. Although she is arguably one of the most experienced and best-prepared candidates for the presidency in American history, she has weaknesses that could undermine her potential to be a great president.

Like the rest of us, she occasionally makes mistakes. Sometimes, she responds with defensiveness and a righteous attitude. She projects a siege mentality, implying that the problem is simply caused by her enemies looking for a way to discredit her. What Clinton needs and what the country needs for her is a strong, independent member of her team. It should be someone with authority to tell her when she is wrong or in danger of making an unnecessary miscalculation that could damage her and the country.

A third term Vice President Joe Biden could do this job for her and for us.