Thousands of abortion opponents marched to the Supreme Court on Monday to mark the 39th anniversary of the Roe v. Wade decision legalizing abortion, and supportive lawmakers urged them to further their cause by working to defeat President Barack Obama in the fall.

The "March for Life" has been held every year since 1974, a year after the landmark Supreme Court ruling. It's consistently one of the largest protests of the year in Washington, although soggy, chilly conditions likely kept this year's numbers down a bit.

House Speaker John Boehner addressed the group, reminding those gathered on the muddy National Mall that he's one of 12 children

"I'm sure it wasn't easy for our mother to have 12 of us, but I'm glad we're all here," the Republican lawmaker said. "I've never considered being pro-life a label or a political position. It's just who I am."

Several dozen members of Congress addressed the rally and were cheered by participants, many of whom carried signs reading "I Vote Pro-Life First," ''Defund Planned Parenthood" and "Face It ... Abortion Kills a Person."

Signs endorsing Republican presidential contenders were less ubiquitous, although some in the crowd favored Rick Santorum and Ron Paul, both favorites of conservative Christians.