Facing the toughest re-election battle of his career, John McCain is bringing in the Republican Party's newest rising star in a bid to shore up support among conservative primary voters.
Massachusetts Sen. Scott Brown is making his first campaign trip as senator. His visit to Arizona Friday will be a first test of his popularity among Republican activists after he broke with the GOP leadership to side with Democrats in supporting a jobs bill.
Brown won his seat in January with the help national Republicans, tea party groups, and an array of conservative special interests. Some of those supporters turned against Brown after his Feb. 22 vote on the jobs bill, calling him "Benedict Brown" and lambasting him online.
As a nationally popular Republican representing a left-leaning state, Brown walks a fine line between pleasing his base and positioning himself for re-election.
It's a challenge McCain knows well. Some Arizona conservatives have long been skeptical of him over his own work with Democrats in support of issues including campaign-finance and immigration reform.
Brown's visit is supposed to help the Arizona senator galvanize support on the right. And even as some former supporters turn on him, Brown remains popular in the Republican Party after his victory embarrassed Democrats.
He won a special election to replace the late Ted Kennedy, a liberal icon who frustrated conservatives for half a century.
Brown's victory gave Republicans the crucial 41st vote they need to block Democratic legislation in the Senate. On his first opportunity to do so, however, he was one of five Republicans to prevent a filibuster and allow the jobs bill to advance. It later passed the Senate on a formal vote with support from 13 Republicans.
Brown is in Arizona for campaign stops with McCain in Phoenix on Friday and Tucson on Saturday, as well as a fundraiser in the Phoenix suburb of Scottsdale.
His visit pays back McCain, one of Brown's earliest supporters when his victory looked like a long shot and he struggled to find a footing in the race. It also provides the first test of Brown's ability to raise money for Republican candidates.
Days after his election, Brown recorded a phone call asking Arizona Republicans to support McCain.
The campaign stop comes just days after the leaders of four key Arizona tea party groups announced they would not endorse any candidate in the race, a blow to McCain's GOP primary opponent, who has tried to define himself as the race's tea party candidate.
J.D. Hayworth, a former congressman and conservative talk-radio host, announced in January that he would challenge McCain for the seat he's held since 1986.
Hayworth says McCain's past work with Democrats shows he can't be trusted to uphold conservative values. McCain has worked with Sen. Russ Feingold of Wisconsin to restrict campaign donations and with Kennedy on a bill that would have created a pathway to citizenship for illegal immigrants.
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