Cruz no favorite with fellow Republican senators

Worse than that, many GOP lawmakers and aides fear the Texas senator could ruin Republicans' chances of hanging onto control of the Senate in November's elections, alienating voters in a half-dozen key swing states with his hardline stances on issues from immigration to abortion.

Any attempt to weaken Cruz in his primary campaign against Donald Trump and other GOP candidates risks bolstering his argument that he's running against the "Washington cartel."

In the presidential primaries, Cruz has attempted to make a virtue of his rejection by the Washington establishment, and his allies say he will actually help fellow Republicans by energizing the base and turning out evangelicals and others.

[...] with Democrats optimistic they might win the five seats needed to retake control of the Senate — four if they keep the White House — Republicans are desperate to protect vulnerable incumbents in states like Pennsylvania, Ohio and New Hampshire, where a Cruz candidacy could turn off independents.

[...] Cruz has become such a pariah that one of his colleagues, Sen. Richard Burr of North Carolina, told supporters at a campaign fundraiser for his own re-election that he would vote for liberal Sen. Bernie Sanders for president before Cruz, according to one person who attended the event.

In December 2014, Cruz again infuriated fellow Republicans when he kept the Senate in session in a failed bid to oppose Obama's immigration policies.