WASHINGTON (Reuters) - New U.S. Trade Representative Robert Lighthizer started work on Monday, vowing to help reverse a “dangerous trajectory” of U.S. trade and making plans to meet with lawmakers over the NAFTA trade deal and attend a Pacific trade ministers conference in Vietnam. Lighthizer, a veteran trade lawyer and deputy USTR during the Reagan administration, was sworn into office by Vice President Mike Pence, capping months of delays and filling the last open seat in President Donald Trump’s cabinet. Lighthizer will be one of three key leaders on trade policy, working alongside Commerce Secretary Wilbur Ross and White House trade and industrial policy adviser Peter Navarro. All three have vowed to help shrink chronic U.S. trade deficits through stronger enforcement of U.S. trade laws and to negotiate deals that boost U.S. exports without leading to jobs and factories migrating overseas.   “When my grandchildren, who are here today, talk to their grandchildren, they will say that President Trump permanently reversed the dangerous trajectory of American trade, put America first and made our farmers, ranchers and workers richer and the country safer,” Lighthizer said. “I hope I can make some small contribution to that accomplishment.” Lighthizer, 69, will be the principal U.S. negotiator in talks expected to start later this year to revamp the 23-year-old North American Free Trade Agreement with Canada and Mexico. On Tuesday, he will start two days of meetings with members of key trade-related panels in Congress, a spokeswoman for the Senate Finance Committee said. The meetings are required before USTR can formally launch the formal renegotiating process with a 90-day consultation period. White House Press Secretary Sean Spicer also said Lighthizer will attend the May 20-21 meeting of trade ministers from the 21 Asia-Pacific Economic Cooperation (APEC) countries in Hanoi, Vietnam. At that meeting, Lighthizer will face many counterparts who were signatories to the Trans-Pacific Partnership, the 12-country free trade agreement from which Trump withdrew in January. Some countries, including Japan, have been exploring options to revive TPP without the United States. China, the largest U.S. trading partner, also is a member of APEC, allowing Lighthizer an opportunity to meet his Chinese counterparts as the Trump administration seeks to build on agreements to shrink the U.S. trade deficit with China. Last week, Commerce’s Ross said the United States and China had agreed to take action by mid-July to increase access to Chinese markets for U.S. beef, financial services and liquefied natural gas. 