ZIONSVILLE, Pa. - It’s a gray early spring morning in the Lehigh Valley when Pat Toomey slides into the leather passenger seat of an aide’s Ford Explorer.

The Republican U.S. senator scans his itinerary, laid out meticulously in a white three-ring binder. A memo for each event lists a one-sentence "purpose," then background and talking points: "Great to Be Here With You Today," "Wawa's Leading by Example," "Overwhelming Bipartisan Support."

His planned speech honoring Sister Mary Scullion, the Philadelphia advocate for the homeless and mentally ill, includes pronunciation: SKULL-E-ON.

Toomey aide Steve Kelly drives while the senator marks changes with a blue felt-tip pen, writing in neat block letters.

Slim and 53, Toomey wears a charcoal, pinstriped suit and French-cuffed shirt. He chews the arms of his rimless glasses when he pauses in thought. His forehead is marked by deep furrows.

In many ways, this will be a typical day in Pennsylvania for the first-term senator: meetings with business leaders and health advocates, a political luncheon, a judge's swearing-in, and two speeches.

Looming, though, is a high-stakes political storm. Toomey's run for reelection next year is one of a handful of races that will decide control of the Senate, and whether the next president has a chamber that advances his or her agenda, or attacks it.

Eyeing a swing state that tilts blue in presidential years, Democrats have made him a top target.

The heat of the race - policy debates and gritty tactics - is still months away, but a few days with Toomey offer a view of how he prepares, how he operates, and his deliberate moves toward the fray.

Philadelphia | April 24

Kelly's Explorer pulls up to Wawa's headquarters in Media, where Toomey meets with four Wawa executives before speaking at an event for veterans.

A former derivatives trader and fiscal hawk, the senator likes things quantified: How many people work in a Wawa store? What percentage of employees get company stock?

When CEO Chris Gheysens brings up tax reform - a priority for the business community - Toomey laments flaws in the tax code. He calls it "ridiculous" - one of his go-to ways of describing problems or opposing ideas. His plans, by contrast, are "common sense" or "reasonable."

After the event, Kelly drives to Toomey's Center City office, where he types up an updated set of notes. Toomey scans them. Satisfied, he folds the pages into perfect thirds, pressing in ruler-straight creases with his palm, and tucks them into his jacket.

At a Union League lunch honoring Scullion, Toomey opens, as he often does, by poking fun at his stump skills. The buttoned-up senator doesn't warm a room. His voice rarely rises above a monotone, though his dry delivery lends itself to self-deprecating sarcasm.

He tells the crowd that his fellow Pennsylvania senator, Democrat Bob Casey, gave him frank advice: "Just because it can't be a good speech, doesn't mean it can't be a short speech."

Everyone laughs.

Around the same time, a short drive away in Montgomery County, Allentown Mayor Ed Pawlowski is announcing his campaign for Toomey's seat. Another Democrat, Joe Sestak, the former congressman from Delaware County, is already deep in his campaign, blasting out daily critiques of Toomey's record.

Throughout the day, Toomey never mentions them or the race, and gently rebuffs questions about the competition. "Anyone who wants to run can run," he says blandly.

Toomey for months has said his focus is on governing. He has a strategy and plan and isn't straying.

But he is preparing. Two days earlier, records show, Toomey's campaign had collected yet a few more $2,600 checks. With 18 months to the election, he has $8.3 million on hand.

After the Explorer settles back into his Zionsville driveway, Toomey - an avid gardener - shows off last summer's project: a tree house for his three kids, ages 15, 13, and 5. The former Eagle Scout designed and built it himself.

Every angle and plank appears aligned to perfection.

Washington | June 23

In a ballroom bathed in green light, Toomey stands on stage at the Ritz-Carlton.

"Our common sense proposition was this: There is indeed a constitutional right for law-abiding people to own guns, but there's no such right for violent criminals, or for those whose mental incapacities make them a danger to society," he says.

Applause interrupts him.

It's just one week after the deadly church shooting in Charleston, S.C., an act that reignited the debate on guns. This gala has been organized by relatives of children and teachers killed in 2012 at Sandy Hook Elementary School in Newtown, Conn.

Toomey jokes that the event feels like the time he accidentally walked into the Democrats' lunch room: All the other officials here are Democrats backing tougher gun laws.

He's being honored for sponsoring a bill after the Newtown massacre to expand background checks to more gun buyers - an indelible moment from his first term, but one he has rarely talked about since the measure failed.

Tonight, he returns to the issue in terms that break from his analytical style, with personal details he has never publicly mentioned. He describes how he and his wife, Kris, thought of their children as they watched news reports from Sandy Hook.

"My only regret," he concludes, "really, is that it took me so long to raise my voice on this very important issue."

This isn't a campaign event, and it was planned long before the Charleston shooting. Still, the opportunity doesn't escape Toomey's team.

As the gala approached, they had blitzed reporters with reminders and news releases about his award. He follows up by going on MSNBC and joining in a media conference call.

This is how Toomey hopes voters see him: a Republican willing to reach for the middle ground.

After riding the Tea Party wave to office in 2010 and chasing Arlen Specter from the party, he acknowledges that he "was then and am now more conservative than Arlen Specter." But he says his record is one of a "constructive conservative" willing to work with anyone "who wants to make progress."

Convincing voters will be critical in 2016, when he is expected to face a left-leaning electorate possibly energized by a female presidential candidate.

Democrats argue that the gun bill, mild persona, and some moderate votes can't disguise Toomey's far-right record. The day before the gala, Sestak aides had reminded reporters that Toomey voted against a ban on assault weapons.

Pittsburgh | June 30

Lobster rolls and fried calamari fill the plates in the back room at Roland's Seafood Grill in the city's Strip District.

But the audience, a few dozen Allegheny County young Republicans, politely waits to dig in as Toomey lays out the race, methodically ticking off advantages: Democrats are divided, fund-raising is strong, voters will want change after eight years of Obama.

"Fundamentally, it's all good," he says. "But let's be candid, right? In the end this is going to be a close, hard-fought battle."

The group had long sought Toomey as a guest speaker. In turn, he asks for their help.

"Our presidential nominee and I both are going to need your support," he says, but, "if we win this, I mean, just think about what's at stake."

Toomey lays out the tantalizing vision of a House, Senate, and White House, all in Republican hands.

He's moving toward campaign mode.

This day, his campaign has launched its first TV ads, promoting his bill to shield children from molesters, a measure that might soften his numbers-crunching image.

Kelly has left the Senate staff to join the campaign. A Toomey 2016 Twitter account has sprung up. Allies on the right are attacking Sestak and lining up ads praising Toomey as "constructive."

At the tavern, Toomey takes questions from the group, easily pivoting between topics. Rather than retail charm, he relies on razor sharp arguments, stripped down and delivered with logical efficiency: problem, solution, rebuttal to counter-arguments. He punctuates his points with deadpan wonk humor.

He only stumbles here when asked to pick among GOP presidential candidates. Toomey tucks his hands in his pockets and hesitates before explaining: "There's several of them I have to work with every day."

When an official from a small town outside Pittsburgh asks about the Clean Water Act, Toomey quickly dissects the issue.

The Environmental Protection Agency, he says, is "completely redefining" the waters it claims jurisdiction over, going far beyond the "navigable waterways" for which Congress gave it oversight.

It's another example of government overreach, just the kind a Republican Senate should rein in.

"I don't know about you," Toomey says, but to qualify as navigable, "You probably ought to be able to float a canoe - is that reasonable?"

The crowd chuckles.

Though Toomey begins the race as a slight favorite, a vivid memory is a reminder of the fight ahead: It was the first race he saw up close, in 1994 when he helped a friend in Allentown challenge a Democratic congressman.

His friend lost in a tight race. This number stuck with Toomey - 471 votes.

He took it as a lesson: Don't assume an incumbent is invulnerable, says the man who challenged Specter and now braces for another scrap.

"That," he says, "really caught my attention."

Here in Pittsburgh, Toomey tells young Republicans that next year’s race will “go right down to the wire - because it’s Pennsylvania, Pennsylvania in a presidential year.”