Full Title: Trump expected to announce gun control legislation this week. But the substance of it is a mystery The Trump administration is expected to announce its proposal to curb gun violence as soon as next week. But after the Democrats' fiery debate on gun control, what President Trump will support is far from clear. The White House has been talking to a trio of lawmakers: Democrats Chris Murphy and Joe Manchin and Republican Pat Toomey. They all support tougher background checks. After the recent mass shootings in Dayton, Ohio and El Paso, Texas, Mr. Trump called for gun control...