Inside the Obama-Shapiro Relationship

In 2007, a Pennsylvania state representative named Josh Shapiro broke with much of the Democratic establishment to back for president a first-term senator from Illinois named Barack Obama.

Mr. Obama, who lost Pennsylvania’s 2008 primary to Hillary Clinton but won the presidency, did not forget it.

Over the nearly two decades since that early endorsement, Mr. Shapiro and Mr. Obama remained in touch, developing a connection that is closer than is commonly understood, according to interviews with people who know them both. Now, Mr. Shapiro is a popular governor in a crucial battleground state who could join a presidential ticket himself, as Vice President Kamala Harris, another early Obama supporter, weighs her running-mate options.

The relationship between the two men offers a window into the instincts and influences of one of Ms. Harris’s top choices.

“Josh was one of our earliest supporters in 2008 in Pennsylvania, when almost all the political establishment was with Hillary,” David Plouffe, who managed Mr. Obama’s campaign that year, said in a text message on Thursday. (Separately, on Friday, the Harris campaign announced that Mr. Plouffe had joined as a senior adviser.)

“They spent a lot of time together, and Obama thought from Day 1 he had a super high political ceiling,” Mr. Plouffe added. “He stuck with us during the bad times, including us getting pummeled in his home state, and never shied from a single thing we asked him to do.”