In the last two weeks, Republican frontrunner Donald Trump has won more delegates in primaries and caucuses, even while his opponents have launched new attacks and questions have been raised about his supporters.  The week's Economist/YouGov Poll finds Trump still at the top of GOP voters' preference with a wider lead, while Florida Senator Marco Rubio seems most damaged by the two weeks of attacks and counter-attacks.

This is the first time Trump has garnered the support of a majority of Republican primary voters nationwide. YouGov's February 24-27 survey marked his previous high, at 44% support.

Two weeks ago, the national Economist/YouGov Poll showed Rubio and Texas Senator Ted Cruz battling for second place behind Trump, in a field which still included retired neurosurgeon Ben Carson (who has since endorsed Trump).  This week, Rubio is battling Ohio Governor John Kasich for last place, with half the support Republican voters give to Cruz.  He is behind both Cruz and Kasich when Republican voters are asked for their second choice.  And only 19% of Republican voters would be enthusiastic about a Rubio nomination (in contrast, half would be enthusiastic if Trump were the nominee).