Donald Trump took a shot at Hillary Clinton after Vice President Joe Biden announced he wouldn't run for president Wednesday. Reuters

After Vice President Joe Biden announced in an impassioned speech Wednesday that he would not run for president in 2016, Donald Trump joined the fray of candidates honoring his choice on Twitter and used the opportunity to prod Democratic front-runner Hillary Clinton. The real estate magnate, who is leading the Republican field, jabbed at Clinton's record, saying that he prefers a run against her anyway.

It's not exactly out of character, of course, and Trump frequently tweaks other candidates as well. He frequently targets his Republican opponents like former Florida Gov. Jeb Bush or Florida Sen. Marco Rubio. One of the most recent spats erupted when Trump noted that the 9/11 terrorist attacks occurred on his brother's watch. Bush defended his brother's record of "keeping us safe."

Trump's refusal to play nice during the campaign has benefited him so far. He has soared in the polls since he announced in June. Recently, the Republican establishment has been re-evaluating if he could win. Some are beginning to say that his steady polls, which have outlasted other early spikes in presidential campaigns, indicate that he could actually become the Republican nominee.

In averages of national polls aggregated by Real Clear Politics, Trump is the clear front-runner, beating his closest rival Ben Carson -- who has been catching up -- by 5.9 points. Trump currently sits at 27.2 percent of the national Republican vote. He's also the leader in early nominating states, and takes in 28 percent of the vote in New Hampshire, and 22.3 percent in Iowa.