WASHINGTON — Ask Sen. John McCain about his popularity on Twitter and he's quick to respond.
"One million seven hundred and forty-one thousand," the 73-year-old Arizona Republican said, reciting the number of his followers on the third-most-popular social-networking site in the United States.
McCain, who said during his 2008 presidential bid that he didn't use e-mail and was learning to get online, is among about 200 members of Congress who tweet — sending messages of 140 characters or less — about topics as varied as policy and politics to food and sports.
"I love it; it's so interactive," said McCain, who has more than 46 times as many followers on Twitter as the next most popular member of Congress, Sen. Claire McCaskill, D-Missouri.
The surge in the political use of social-networking sites such as Twitter is likely to grow as more lawmakers realize its effectiveness as a way to reach and hear from voters, said Darrell West, director of governance studies at the Brookings Institution.
"You've got to get out of the bubble," said Rep. Darrell Issa, R-Calif., who sends about four tweets a day, the most of any member of Congress, according to the Web site Tweetcongress.org, which tracks congressional tweeting.
"Wake up with a headache, queasy stomach, bloodshot eyes?" Issa tweeted the morning after the House approved the Democrats' healthcare overhaul bill in March. Using the abbreviated spelling style often favored in such messages, he added: "You're suffering from the HC hangover. Dtch the Advil. I'll post a remedy shortly."
Issa, 56, also used Twitter to hold a photo caption contest for the 2,000-plus-page health care legislation Republicans opposed. One entry read: "Vote yes on Obamacare, lest millions of trees died in vain."
McCain and Issa said they write their own tweets as well as have staff send them.
"A lot of times I sit there with my communications person because she's so much faster than I am," McCain said. "But I do scan it all the time and compose tweets."
Tweets appear on the sender's home page and are sent to followers.
Many lawmakers use Twitter in a narrow way to describe travels and events rather than issues and policy, West said.
"The problem right now is politicians are using it to be hip, but they could be using it in much more meaningful ways," he said. For example, they could explain their votes and link to reports or news conferences, and that is the way West expects the tool to evolve.
McCaskill, 56, lets her 37,394 followers into her life. "Family day at our house. Husband Joe makes grits, everyone gathers. I dote on my grandson. I love Sundays," the senator wrote March 7.
She also briefed followers during a marathon session on health care legislation. "Many of my colleagues reading files, writing, still working between votes," she tweeted March 24, as the Senate met into the morning on Republican amendments.
Minutes later, she sent this update on the Republican proposals: "I will not support any of these amendments that are just masquerading as serious substance. They are only procedural land mines to HC reform."
Chris McCroskey, co-founder of Tweetcongress.org, said the number of lawmakers on Twitter has grown eightfold from 24 in December 2008, with Republicans outnumbering Democrats about two-to-one. McCroskey attributes this to Republicans realizing the potential of social networking after President Obama made use of it during his 2008 campaign.
More lawmakers are likely to adopt it for fundraising and promoting events, West said.