AUSTIN, Tex. — From its start in 1999, the office of the solicitor general of Texas was run by a plain-spoken Mormon, a by-the-books lawyer known for mentoring young attorneys and defending the state, whatever the political consequences.

The young lawyers loved him. The state’s legal community hailed him as a man of dignity and integrity. And the office seldom showed up in the headlines.

But everything changed in January 2003, when Ted Cruz took over.

Within months of his appointment to the job, Mr. Cruz, then 31, set about transforming this under-the-radar, apolitical office into an aggressively ideological, attention-grabbing one. From a nondescript government building in the shadow of the Capitol, he inserted himself into scores of politically charged cases around the country, bombarding the United States Supreme Court with amicus briefs on hot-button issues like abortion and gun control.

His focus on gaining attention clashed with the sensibilities of many of the lawyers who worked for him and were accustomed to a more scrupulous and less publicity-minded approach. Before the end of his first year, half of the eight attorneys working in the office had left, raising concern inside the attorney general’s office about whether Mr. Cruz was the right choice for the job.