Republican presidential candidate Sen. Rand Paul, R-Ky., speaks during the first Republican presidential debate at the Quicken Loans Arena Thursday, Aug. 6, 2015, in Cleveland. AP Sen. Rand Paul (R-Kentucky) is trying to intensify a fight with current Republican presidential front-runner Donald Trump.

Paul's campaign on Monday announced a conference call with reporters specifically dedicated to Trump. During that call, Paul slammed the real-estate magnate for conducting a substance-less presidential campaign and making derogatory comments about women.

"The truth telling is bluster, the truth-telling is non-sequitur, self-aggrandizement, but is there really anything substantive coming out of saying that people are fat, people are stupid?" Paul said of Trump.

Calling Trump a "fake conservative," Paul listed off the issues where Trump has agreed with Democrats in the past, including supporting the 2008 bank bailouts, supporting some stricter measures on gun ownership, and saying that a single-payer healthcare system "could have worked."

Paul's broadside caused Trump to respond with one of his own Monday evening. Writing on Twitter, the real-estate developer declared that Paul was "truly weird" and "reminds me of a spoiled brat without a properly functioning brain":

But Paul's attacks didn't go as far as some of his opponents in criticizing Trump's most recent round of controversial statements.

Paul dodged an opportunity to hit Trump's comment Friday that Fox News host Megyn Kelly had "blood coming out of her eyes, blood coming out of her whatever." Those comments have been interpreted as sexist and have been widely criticized by Republicans and Democrats alike; Trump insists he meant nothing lewd and only a "deviant" would interpret something inappropriate from what he said.

"While some people are excited by fat jokes and stupid jokes, there are a lot of people in the general election— independents as well as women voters — are not that entertained by this," Paul said. "What we'll end up with is a reality-TV star as a nominee if we're not careful."

Republican 2016 U.S. presidential candidates Wisconsin Governor Scott Walker (L) and former Florida Governor Jeb Bush (R) watch as businessman Donald Trump (C) reacts to a question at the first official Republican presidential candidates debate of the 2016 U.S. presidential campaign in Cleveland, Ohio, August 6, 2015. REUTERS/Brian Snyder

Though Paul has said in the past that he doesn't like to comment on other candidates, he has recently begun publicly criticizing the real-estate mogul. During the opening minutes of last week's presidential debate, Paul jumped on Trump's refusal to say whether he'd rule out a third-party run.

Paul said that he changed his mind on confronting Trump because someone has to do it.

"If no one stands up to a bully, a bully will just keep doing what they're doing," Paul said. "I'm happy to do it."

Though the top-tier candidates have been mostly reserved in their criticisms of Trump, many of the lower-polling candidates have taken to knocking the real-estate magnate.

On Monday, Louisiana Gov. Bobby Jindal (R) "joked" that he would start randomly dropping Trump's name in sentences in order to get people to pay attention to his message.

Last month, Sen. Lindsey Graham (R-South Carolina) also complained that he may be getting more attention for his attacks on Trump than his actual policy positions.

“If my numbers go up just because I call Donald Trump a 'jackass,' that’s not why I want to rise in the polls,” Graham said on MSNBC in July.

For his part, Trump has embraced the counterpunch and often takes shots at those who criticize him. After former Hewlett-Packard CEO Carly Fiorina bashed his "blood" comment, for example, Trump wrote on Twitter that her voice gives people headaches: