Senate Minority Leader Mitch McConnell has firmly dug in on refusing GOP help to renew the US's ability to pay off its bills, known as the debt ceiling. Instead, the Kentucky Republican said it's up to Democrats to raise it in order to finance their social spending plans on healthcare, education, and childcare. He insists he's not "bluffing." But the conundrum could have a coin-sized solution. A loophole in the law that prescribes the types of coins that can legally be minted in the US theoretically allows the Treasury Department to mint a $1 trillion platinum coin, deposit it at...