Barack Obama is closing in on Democratic presidential rival Hillary Rodham Clinton’s advantage among superdelegates, building on his lead in the primary race even as he faces troubled times.

Party leaders are encouraging superdelegates to pick a side by late June to prevent the fight from going to the national convention in August, and it seems some are listening as the race enters its final five weeks of voting.

Chelsea Clinton got a superdelegate for her mom while campaigning in Puerto Rico on Wednesday, just as Obama press secretary Bill Burton sent out a statement announcing the support of Rep. Lois Capps. The statement didn’t mention the personal connection — Capps is Burton’s mother-in-law.

Clinton had a big jump start among superdelegates, many of whom have ties to the Clintons and backed her candidacy early on. But most of the superdelegates taking sides recently have gone for Obama, who has won more state contests.

Obama trails Clinton by just 20 superdelegates, 243-263, cutting her lead in half in less than two months. This week, he picked up seven delegates to her four.