The Canadian, Australian and New Zealand dollars all fell solidly on Thursday, tracking a drop in oil prices.
The dollar was on the defensive on Thursday, with investors low on incentives to buy the greenback.
The dollar struggled to recover ground against other major currencies on Tuesday.
Brazil's government said on Monday it is committed to reforms after S&P threatened to downgrade the country further into junk territory.
The dollar slipped to a more than six-month low against a basket of currencies on Monday.
The latest political scandal to hit Brazil is likely to put an end to President Michel Temer's term before the end of 2018, an analyst told CNBC on Monday.
Marcos Casarin, head of Latin American macro research at Oxford Economics, discusses the implications of a leaked audio of Brazilian President Michel Temer.
The fall in the Brazilian real could be good news for the EM Asia currencies, says Khoon Goh, ANZ Research.
The dollar was on track to record its worst week since August on Friday, having given up almost all the gains made since Trump was elected.
Discussing the threat of market contagion from Brazilian stocks and the Brazilian real with Win Thin, Brown Brothers Harriman global head of emerging market strategy.
The U.S. dollar rose against a basket of major currencies on Thursday.
Michel Temer gave his blessing to an attempt to pay a potential witness to remain silent in the country's biggest-ever graft probe.
The yen rose to its highest in two weeks and the Swiss franc hit a seven-week high against the U.S. dollar on Wednesday.
The euro surged more than 1 percent against a broadly weaker dollar on Tuesday, rising above $1.10.
The Canadian dollar hit its highest level in two weeks and the Australian dollar was at a 10-day high.
The U.S. dollar fell on Friday, easing from a roughly two-month high against the yen.
The New Zealand and Canadian dollars sank on Thursday as domestic concerns outweighed a bounce in oil prices for the currencies.
Trump abruptly fired FBI Director James Comey in a move that shocked Washington and dampened some of this week's strong risk appetite.
Currency markets swung back to trading on the diverging outlooks for growth and tighter monetary policy.
Meanwhile, a fall in oil prices drove the Australian dollar and Canadian dollar to new lows.