We provide conditions under which linear combinations of normalized elementary symmetric polynomials satisfy some Newton-like inequalities. Namely, the log-concavity of the coefficients and nonnegativity of the arguments. We prove that such conditions are essential. That is, dropping any of these conditions leads to counterexamples. This settled a conjecture of Ren [C. Ren, A generalization of Newton-Maclaurin's inequalities, Int. Math. Res. Not. IMRN 5, (2024), 3799-3822].