We combine the mollifier method with a zero detection method of Atkinson to prove in a new way that a positive proportion of the nontrivial zeros of the Riemann zeta-function 16000895&_mathId=si1.gif&_user=111111111&_pii=S0022314X16000895&_rdoc=1&_issn=0022314X&md5=68e6d6ed367871fb848bebd39027b87a" title="Click to view the MathML source">ζ(s) are on the critical line. One of the main ingredients of the proof is an estimate for a mollified fourth moment of 16000895&_mathId=si1.gif&_user=111111111&_pii=S0022314X16000895&_rdoc=1&_issn=0022314X&md5=68e6d6ed367871fb848bebd39027b87a" title="Click to view the MathML source">ζ(s). We deduce this estimate from the twisted fourth moment formula that has been recently developed by Hughes and Young.