PHILADELPHIA — The AFL-CIO will endorse President Joe Biden ahead of his rally with union members in Philadelphia on Saturday, according to two sources familiar with the plan. The vote of the general board, which represents 12.5 million members and 60 affiliated unions, is slated to happen Friday on a Zoom call. Biden will speak to union members at the Convention Center on Saturday, marking the first political event of his presidential reelection campaign. The endorsement isn’t a surprise — the union also backed Biden’s 2020 presidential bid — but it comes about a year earlier than the vote la...