Top Republican: You didn't hear much about our message Monday, but you will tonight
But, he said, look forward to tonight. The Iowa Republican told reporters at a Cleveland restaurant "you're going to hear it more today" from House Speaker Paul Ryan and from Trump himself.
He called Ryan's policy agenda a "very, very positive message."
"Very broad, yet very much in principle," he said. "Maybe lacking in some detail, but it says where the Republican Party is going to go under Ryan's leadership. And then, if Trump's ... got it figured out right ... he said he agrees on 95% of the stuff [with Ryan].
"If they've gone through that Ryan platform very carefully and talked about the main points in it and they agree 95% of the time, I don't know how many more times you can agree," he said. "I might read it and agree with it 90% of the time."
Ryan said Monday morning at a breakfast for the Pennsylvania delegation in Cleveland that Republicans could not win the general election simply by bashing President Barack Obama. They must provide an alternative plan, he said, touting his policy proposals.
That message wasn't exactly heeded at the first night of Donald Trump's Republican National Convention.
Well over three hours' worth of speakers - headlining an event focused on "making America safe again" - hammered Obama and presumptive Democratic nominee Hillary Clinton on all aspects of national security, sweeping the base that helped nominate the Manhattan billionaire into a fervor.
Only Trump's wife, Melania, seemed to offer language more enticing to independents still on the fence over who to vote for this fall. But she appeared to lift parts of her address from Michelle Obama's speech at the 2008 Democratic National Convention.
As noted by The Washington Post's James Hohmann, most of the speeches seemed better placed at the CPAC conservative conference than at the Republican National Convention, where the GOP is looking to attract votes from outside the base in hopes of propelling it over the top in November.
Grassley also spoke about fellow Iowa Sen. Joni Ernst's speech, which was bumped to begin very late during Monday night's program.
"The reason she was pushed back was because someone spoke too long," he said. That's not her fault."
The chair of the Senate Judiciary Committee touted Ernst's speech as "very substantive" on national security.
He joked that the Monday speeches, which he watched on TV, ran too late for him.