American lawmakers are concerned that Facebook's Libra cryptocurrency may try to challenge the dollar and are demanding the company stand down. They want Facebook to immediately halt development of Libra until regulators have time to examine the plans and "take action," according to a letter sent Tuesday to the company by a group of lawmakers from the House Financial Services Committee. Chairwoman Maxine Waters, a Democrat from California, first suggested a moratorium on development the day Libra was announced. The new letter represents an escalation of pressure on Facebook's digital currency plans, which have also been scrutinized by regulators around the world. Other interest groups have weighed in, too: More than 30 organizations sent a similar request to Facebook on Tuesday, saying US and foreign regulatory systems are not prepared to address questions about "national sovereignty, corporate power, consumer protection" and other issues raised by the project.