The secret balloting elevated Mr. Blunt, a former House leader and Mr. Romney’s chief advocate on Capitol Hill, to vice chairman of the Republican conference, the fifth-most-senior position in the party’s caucus.
Senate Republicans also elected Sens. John Thune of South Dakota as chairman of their conference and picked Sen. John Barrasso of Wyoming to be chairman of the SenateGOP policy committee, respectively the third- and fourth-most-senior positions in the party’s Senate caucus.
The Blunt-Johnson race was considered symbolically important, a test of tea party clout a year after the libertarian-leaning movement helped drive Republicans into the House majority.
Mr. Blunt is one of the more established Washington Republicans and controls what is widely considered the best fundraising network of anyone in the party not running for president.
The conference vice-chairmanship position carries little power or responsibility other than to spread the Senate Republican leadership’s message ahead of the 2012 elections. But it often is a steppingstone to higher positions in the seniority-driven chamber.
Mr. Blount was House majority whip and briefly majority leader before Republicans lost their House majority to Democrats in the 2006 election.
Mr. Johnson announced his candidacy soon after Tennessee Sen. Lamar Alexander said in September that he would relinquish the position at the end of the year. Mr. Johnson was endorsed by Sen. Jim DeMint of South Carolina, a prominent figure in the tea party movement.