What you hear from the candidates at a rally is quite insignificant. Jeb today was at a JEB RALLY in SC and his speech was to simply criticize the front runner, a non-politician Donald Trump. Who shows up at a Jeb Bush rally? Those folks that are already, have been committed to Jeb. What does he gain? Very little to nothing. He might as well be home speaking to mommy and daddy.
Its not just Jeb, who shows up at a Rubio rally? Rubio supports, they were already on the Rubio wagon. Cruz? The same thing. Trump, absolutely! However, who has the largest crowds? Trump!!
The only way to gain ground, gain voter support, you MUST hit the streets.