WASHINGTON - Bob Casey is getting into fighting shape.

The soft-spoken Democratic senator, usually found holding press calls on wonky topics such as home heating aid, early childhood education, or the intricacies of Middle East policy, has spent recent weeks at the heavy bag, pounding at the hottest political battles of the moment.

He stood alongside Democratic leaders for a smackdown linking Republican senators to Donald Trump. He blitzed Pennsylvania rallying support for Hillary Clinton. And he held repeated news conferences on the Supreme Court fight, pressing Republicans to "do your job."

He even took to Twitter on Friday to praise liberal favorite Elizabeth Warren, countering the criticism of her presidential qualifications from former Gov. Ed Rendell.

The newly aggressive Casey says he is motivated by revulsion at Trump and GOP obstruction.

But as his home state prepares to host the Democratic National Convention next month, many operatives also see a senator muscling up for his 2018 reelection bid, taking on issues likely to enthuse Democratic voters.

"He has done extraordinarily well when it comes to the business of government," said Jim Burn, former chairman of the Pennsylvania Democratic Party, but "sometimes those in his Democratic base would appreciate a little more red meat, and in the past that has been noticeably lacking from him."

Burn added, "It is refreshing to see some more political emotion and political passion."

Casey's barrage - including press events at Independence Hall and outside the Supreme Court - has reverberated in this year's Senate race in Pennsylvania, one of the country's most critical.

Senate protocol says Casey will not campaign directly against his home-state colleague, Republican Sen. Pat Toomey. But when Casey raises Trump or the court fight, he shines a spotlight on the very topics Democrats are using to batter Toomey.

Casey hustled to Washington during a Senate recess to meet with Supreme Court nominee Merrick Garland - just as liberal groups staged protests outside Toomey's offices urging the Republican to support a vote on the president's pick. News reports on Casey's meeting pointed out the split between him and Toomey, who until then was reluctant to sit with Garland.

The next day, Toomey announced that he would, in fact, meet the nominee.

Casey later stood with top Senate Democrats as they tried to link GOP lawmakers to Trump, the same week the party's Senate campaign arm launched a push to tie vulnerable incumbents like Toomey to the New York billionaire.

Of course, political jabs don't come naturally for a senator who is usually most comfortable citing economic papers and statistics.

After the aggressive New York Sen. Charles Schumer laced into Senate Republicans over Trump, Casey took the microphone and began:

"When I step back and consider what the Republican agenda has been in the Senate over the last couple of years, at least since 2009 - you might even go back further - but at least since 2009, let me provide at least my summary of what I see coming out of that caucus. . . ."

Democratic political operatives and aides close to both Casey and Toomey said they don't believe the Democrat is trying to pile on his Keystone State colleague. The two senators cooperate on home-state issues, and Casey has avoided criticizing Toomey directly.

Casey said his burst of activity stemmed from concern about Trump and Republicans' "outrageous" refusal to hold a hearing on Garland's nomination.

"When you feel strongly about something, you've got to fight hard," he said in his Senate office.

Even there, Casey was more aggressive than usual, criticizing Republicans for an "obsession" with ensuring that "rich people get gross tax cuts."

(He also could not help but retreat to his desk to illustrate one point with a graph charting the gap between workers' productivity and their pay.)

Casey "is the farthest thing from a bomb-thrower we have," said Sen. Chris Coons (D., Del.), a neighbor and friend who has joined the Pennsylvanian at several events.

But he and other Democrats said they have to answer Republican tactics.

"The Republican Party has just thrown out so many of the usual norms and conventions of politics that people who are traditionally moderate, noncombative Democrats feel that they have no recourse but to be very aggressive in response," said Matthew Miller, a Democratic strategist and former spokesman for the party's Senate campaign operation.

Casey is also well aware of his reelection. He is raising money aggressively already, including holding an event at the Pennsylvania Society gathering in New York last December.

He downplayed political motivations, though. Instead, he said that he felt a responsibility to speak out as he becomes more senior - he is now in his 10th year in the Senate - and that national issues always come to the fore in presidential election years.

Casey said his policy priorities, including national security and education programs, would be far better served with a Clinton presidency and a Democratic-led Senate.

That's part of the reason he endorsed Clinton early, he said, in April 2015.

Casey also had some repairs to do: He sided against Clinton, and with then-Sen. Barack Obama, in the 2008 Democratic presidential primary. He may now need her support, and that of the Democratic establishment, in his 2018 midterm reelection campaign, when Democratic enthusiasm typically sags and Republicans expect to be on the offensive.

Over the years, Casey's critics - including his 2012 Republican challenger, the late Tom Smith - have often labeled him a sleepy presence with too little clout. His supporters say he has been a fighter for the party but does not take credit because sharp rhetoric and claiming the spotlight aren't his style.

At one Capitol news conference blasting Republicans over the Supreme Court vacancy, a reporter asked Casey if GOP resistance might hurt Toomey's reelection bid.

"Oh, I don't know," he replied. "I leave that to the political scientists to prognosticate."

A moment later the pugnacious Democratic Senate leader, Harry Reid of Nevada, grabbed the lectern to say polls showed Republicans would, indeed, face voters' wrath.

"Bob being the nice guy he is," Reid explained, "he wasn't in on the meeting yesterday where we had those numbers given to us."

@JonathanTamari