(Reuters) - Highlights of the day for U.S. President Donald Trump’s administration on Tuesday: Trump knew for weeks that national security adviser Michael Flynn had misled the White House about his contacts with Russia but did not immediately force him out, an administration spokesman says.  Defense Secretary Jim Mattis is playing down any impact that Flynn’s resignation might have on Mattis’ debut trip this week to Europe to meet NATO allies. RUSSIA-UKRAINE Trump has said he expects Russia to return Crimea to Ukraine and reduce violence in Ukraine, White House spokesman Sean Spicer says. Russia’s prospects for better relations with Washington appear to have suffered another setback with the resignation of Trump’s national security adviser being the biggest blow yet. The most consequential legal challenge to Trump’s travel ban will proceed on two tracks in the next few days. Congressional Democrats fail to pressure Republicans into seeking Trump’s tax returns after saying the Flynn scandal made it imperative to find out whether the president has business ties to Russia. The Office of Government Ethics says the White House should investigate a public endorsement of Ivanka Trump products by Trump senior adviser Kellyanne Conway and consider disciplinary action.  Four Republican senators have yet to say if they will support Trump’s nominee to head the Labor Department, Andrew Puzder, creating suspense about whether he will survive an initial confirmation hearing this week. Prime Minister Benjamin Netanyahu, preparing for a White House meeting with Trump on Wednesday, will work with advisers to align Israeli and U.S. thinking on the Middle East and ensure “no gaps” remain. Federal Reserve Chair Janet Yellen, in response to a warning from a congressman to halt international negotiations in the early stages of Trump’s presidency, says the U.S. central bank has the authority to consult with foreign counterparts and does so to benefit the United States. Canadian officials and trade experts say that although Trump says he only wants to tweak trade ties with Canada, his pledge to renegotiate NAFTA to focus on Mexico is almost impossible. Trump will meet on Wednesday with the chief executive officers of eight large retailers, including Target Corp (TGT.N), Best Buy Co Inc (BBY.N) and J.C. Penney Company Inc (JCP.N), to discuss tax reform and infrastructure improvements, sources say. 